Searched hist:2010 (Results 751 - 775 of 929) sorted by relevance
/gem5/src/sim/ | ||
H A D | SConscript | diff 7768:cdb18c1b51ea Fri Nov 19 19:00:00 EST 2010 Ali Saidi <Ali.Saidi@ARM.com> SCons: Support building without an ISA diff 7733:08d6a773d1b6 Mon Nov 08 14:58:00 EST 2010 Ali Saidi <Ali.Saidi@ARM.com> ARM: Add checkpointing support diff 7492:acc1fbbef239 Tue Jul 06 00:39:00 EDT 2010 Steve Reinhardt <steve.reinhardt@amd.com> sim: fold StartupCallback into SimObject There used to be a reason to have StartupCallback be a separate object, but not any more. Now it's just confusing. |
/gem5/src/mem/ | ||
H A D | SConscript | diff 7780:42da07116e12 Wed Dec 01 14:30:00 EST 2010 Nilay Vaish <nilay@cs.wisc.edu> ruby: Converted old ruby debug calls to M5 debug calls This patch developed by Nilay Vaish converts all the old GEMS-style ruby debug calls to the appropriate M5 debug calls. diff 7768:cdb18c1b51ea Fri Nov 19 19:00:00 EST 2010 Ali Saidi <Ali.Saidi@ARM.com> SCons: Support building without an ISA diff 6876:a658c315512c Fri Jan 29 23:29:00 EST 2010 Steve Reinhardt <steve.reinhardt@amd.com> ruby: Convert most Ruby objects to M5 SimObjects. The necessary companion conversion of Ruby objects generated by SLICC are converted to M5 SimObjects in the following patch, so this patch alone does not compile. Conversion of Garnet network models is also handled in a separate patch; that code is temporarily disabled from compiling to allow testing of interim code. |
/gem5/src/cpu/ | ||
H A D | exec_context.hh | diff 7725:00ea9430643b Mon Nov 08 14:58:00 EST 2010 Ali Saidi <Ali.Saidi@ARM.com> ARM/Alpha/Cpu: Change prefetchs to be more like normal loads. This change modifies the way prefetches work. They are now like normal loads that don't writeback a register. Previously prefetches were supposed to call prefetch() on the exection context, so they executed with execute() methods instead of initiateAcc() completeAcc(). The prefetch() methods for all the CPUs are blank, meaning that they get executed, but don't actually do anything. On Alpha dead cache copy code was removed and prefetches are now normal ops. They count as executed operations, but still don't do anything and IsMemRef is not longer set on them. On ARM IsDataPrefetch or IsInstructionPreftech is now set on all prefetch instructions. The timing simple CPU doesn't try to do anything special for prefetches now and they execute with the normal memory code path. diff 7520:67c670459d01 Fri Aug 13 09:16:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> CPU: Add readBytes and writeBytes functions to the exec contexts. diff 6973:a123bd350935 Fri Feb 12 14:53:00 EST 2010 Timothy M. Jones <tjones1@inf.ed.ac.uk> BaseDynInst: Make the TLB translation timing instead of atomic. This initiates a timing translation and passes the read or write on to the processor before waiting for it to finish. Once the translation is finished, the instruction's state is updated via the 'finish' function. A new DataTranslation class is created to handle this. The idea is taken from the implementation of timing translations in TimingSimpleCPU by Gabe Black. This patch also separates out the timing translations from this CPU and uses the new DataTranslation class. |
H A D | inteltrace.hh | diff 7720:65d338a8dba4 Sun Oct 31 03:07:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> ISA,CPU,etc: Create an ISA defined PC type that abstracts out ISA behaviors. This change is a low level and pervasive reorganization of how PCs are managed in M5. Back when Alpha was the only ISA, there were only 2 PCs to worry about, the PC and the NPC, and the lsb of the PC signaled whether or not you were in PAL mode. As other ISAs were added, we had to add an NNPC, micro PC and next micropc, x86 and ARM introduced variable length instruction sets, and ARM started to keep track of mode bits in the PC. Each CPU model handled PCs in its own custom way that needed to be updated individually to handle the new dimensions of variability, or, in the case of ARMs mode-bit-in-the-pc hack, the complexity could be hidden in the ISA at the ISA implementation's expense. Areas like the branch predictor hadn't been updated to handle branch delay slots or micropcs, and it turns out that had introduced a significant (10s of percent) performance bug in SPARC and to a lesser extend MIPS. Rather than perpetuate the problem by reworking O3 again to handle the PC features needed by x86, this change was introduced to rework PC handling in a more modular, transparent, and hopefully efficient way. PC type: Rather than having the superset of all possible elements of PC state declared in each of the CPU models, each ISA defines its own PCState type which has exactly the elements it needs. A cross product of canned PCState classes are defined in the new "generic" ISA directory for ISAs with/without delay slots and microcode. These are either typedef-ed or subclassed by each ISA. To read or write this structure through a *Context, you use the new pcState() accessor which reads or writes depending on whether it has an argument. If you just want the address of the current or next instruction or the current micro PC, you can get those through read-only accessors on either the PCState type or the *Contexts. These are instAddr(), nextInstAddr(), and microPC(). Note the move away from readPC. That name is ambiguous since it's not clear whether or not it should be the actual address to fetch from, or if it should have extra bits in it like the PAL mode bit. Each class is free to define its own functions to get at whatever values it needs however it needs to to be used in ISA specific code. Eventually Alpha's PAL mode bit could be moved out of the PC and into a separate field like ARM. These types can be reset to a particular pc (where npc = pc + sizeof(MachInst), nnpc = npc + sizeof(MachInst), upc = 0, nupc = 1 as appropriate), printed, serialized, and compared. There is a branching() function which encapsulates code in the CPU models that checked if an instruction branched or not. Exactly what that means in the context of branch delay slots which can skip an instruction when not taken is ambiguous, and ideally this function and its uses can be eliminated. PCStates also generally know how to advance themselves in various ways depending on if they point at an instruction, a microop, or the last microop of a macroop. More on that later. Ideally, accessing all the PCs at once when setting them will improve performance of M5 even though more data needs to be moved around. This is because often all the PCs need to be manipulated together, and by getting them all at once you avoid multiple function calls. Also, the PCs of a particular thread will have spatial locality in the cache. Previously they were grouped by element in arrays which spread out accesses. Advancing the PC: The PCs were previously managed entirely by the CPU which had to know about PC semantics, try to figure out which dimension to increment the PC in, what to set NPC/NNPC, etc. These decisions are best left to the ISA in conjunction with the PC type itself. Because most of the information about how to increment the PC (mainly what type of instruction it refers to) is contained in the instruction object, a new advancePC virtual function was added to the StaticInst class. Subclasses provide an implementation that moves around the right element of the PC with a minimal amount of decision making. In ISAs like Alpha, the instructions always simply assign NPC to PC without having to worry about micropcs, nnpcs, etc. The added cost of a virtual function call should be outweighed by not having to figure out as much about what to do with the PCs and mucking around with the extra elements. One drawback of making the StaticInsts advance the PC is that you have to actually have one to advance the PC. This would, superficially, seem to require decoding an instruction before fetch could advance. This is, as far as I can tell, realistic. fetch would advance through memory addresses, not PCs, perhaps predicting new memory addresses using existing ones. More sophisticated decisions about control flow would be made later on, after the instruction was decoded, and handed back to fetch. If branching needs to happen, some amount of decoding needs to happen to see that it's a branch, what the target is, etc. This could get a little more complicated if that gets done by the predecoder, but I'm choosing to ignore that for now. Variable length instructions: To handle variable length instructions in x86 and ARM, the predecoder now takes in the current PC by reference to the getExtMachInst function. It can modify the PC however it needs to (by setting NPC to be the PC + instruction length, for instance). This could be improved since the CPU doesn't know if the PC was modified and always has to write it back. ISA parser: To support the new API, all PC related operand types were removed from the parser and replaced with a PCState type. There are two warts on this implementation. First, as with all the other operand types, the PCState still has to have a valid operand type even though it doesn't use it. Second, using syntax like PCS.npc(target) doesn't work for two reasons, this looks like the syntax for operand type overriding, and the parser can't figure out if you're reading or writing. Instructions that use the PCS operand (which I've consistently called it) need to first read it into a local variable, manipulate it, and then write it back out. Return address stack: The return address stack needed a little extra help because, in the presence of branch delay slots, it has to merge together elements of the return PC and the call PC. To handle that, a buildRetPC utility function was added. There are basically only two versions in all the ISAs, but it didn't seem short enough to put into the generic ISA directory. Also, the branch predictor code in O3 and InOrder were adjusted so that they always store the PC of the actual call instruction in the RAS, not the next PC. If the call instruction is a microop, the next PC refers to the next microop in the same macroop which is probably not desirable. The buildRetPC function advances the PC intelligently to the next macroop (in an ISA specific way) so that that case works. Change in stats: There were no change in stats except in MIPS and SPARC in the O3 model. MIPS runs in about 9% fewer ticks. SPARC runs with 30%-50% fewer ticks, which could likely be improved further by setting call/return instruction flags and taking advantage of the RAS. TODO: Add != operators to the PCState classes, defined trivially to be !(a==b). Smooth out places where PCs are split apart, passed around, and put back together later. I think this might happen in SPARC's fault code. Add ISA specific constructors that allow setting PC elements without calling a bunch of accessors. Try to eliminate the need for the branching() function. Factor out Alpha's PAL mode pc bit into a separate flag field, and eliminate places where it's blindly masked out or tested in the PC. |
H A D | nativetrace.hh | diff 7720:65d338a8dba4 Sun Oct 31 03:07:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> ISA,CPU,etc: Create an ISA defined PC type that abstracts out ISA behaviors. This change is a low level and pervasive reorganization of how PCs are managed in M5. Back when Alpha was the only ISA, there were only 2 PCs to worry about, the PC and the NPC, and the lsb of the PC signaled whether or not you were in PAL mode. As other ISAs were added, we had to add an NNPC, micro PC and next micropc, x86 and ARM introduced variable length instruction sets, and ARM started to keep track of mode bits in the PC. Each CPU model handled PCs in its own custom way that needed to be updated individually to handle the new dimensions of variability, or, in the case of ARMs mode-bit-in-the-pc hack, the complexity could be hidden in the ISA at the ISA implementation's expense. Areas like the branch predictor hadn't been updated to handle branch delay slots or micropcs, and it turns out that had introduced a significant (10s of percent) performance bug in SPARC and to a lesser extend MIPS. Rather than perpetuate the problem by reworking O3 again to handle the PC features needed by x86, this change was introduced to rework PC handling in a more modular, transparent, and hopefully efficient way. PC type: Rather than having the superset of all possible elements of PC state declared in each of the CPU models, each ISA defines its own PCState type which has exactly the elements it needs. A cross product of canned PCState classes are defined in the new "generic" ISA directory for ISAs with/without delay slots and microcode. These are either typedef-ed or subclassed by each ISA. To read or write this structure through a *Context, you use the new pcState() accessor which reads or writes depending on whether it has an argument. If you just want the address of the current or next instruction or the current micro PC, you can get those through read-only accessors on either the PCState type or the *Contexts. These are instAddr(), nextInstAddr(), and microPC(). Note the move away from readPC. That name is ambiguous since it's not clear whether or not it should be the actual address to fetch from, or if it should have extra bits in it like the PAL mode bit. Each class is free to define its own functions to get at whatever values it needs however it needs to to be used in ISA specific code. Eventually Alpha's PAL mode bit could be moved out of the PC and into a separate field like ARM. These types can be reset to a particular pc (where npc = pc + sizeof(MachInst), nnpc = npc + sizeof(MachInst), upc = 0, nupc = 1 as appropriate), printed, serialized, and compared. There is a branching() function which encapsulates code in the CPU models that checked if an instruction branched or not. Exactly what that means in the context of branch delay slots which can skip an instruction when not taken is ambiguous, and ideally this function and its uses can be eliminated. PCStates also generally know how to advance themselves in various ways depending on if they point at an instruction, a microop, or the last microop of a macroop. More on that later. Ideally, accessing all the PCs at once when setting them will improve performance of M5 even though more data needs to be moved around. This is because often all the PCs need to be manipulated together, and by getting them all at once you avoid multiple function calls. Also, the PCs of a particular thread will have spatial locality in the cache. Previously they were grouped by element in arrays which spread out accesses. Advancing the PC: The PCs were previously managed entirely by the CPU which had to know about PC semantics, try to figure out which dimension to increment the PC in, what to set NPC/NNPC, etc. These decisions are best left to the ISA in conjunction with the PC type itself. Because most of the information about how to increment the PC (mainly what type of instruction it refers to) is contained in the instruction object, a new advancePC virtual function was added to the StaticInst class. Subclasses provide an implementation that moves around the right element of the PC with a minimal amount of decision making. In ISAs like Alpha, the instructions always simply assign NPC to PC without having to worry about micropcs, nnpcs, etc. The added cost of a virtual function call should be outweighed by not having to figure out as much about what to do with the PCs and mucking around with the extra elements. One drawback of making the StaticInsts advance the PC is that you have to actually have one to advance the PC. This would, superficially, seem to require decoding an instruction before fetch could advance. This is, as far as I can tell, realistic. fetch would advance through memory addresses, not PCs, perhaps predicting new memory addresses using existing ones. More sophisticated decisions about control flow would be made later on, after the instruction was decoded, and handed back to fetch. If branching needs to happen, some amount of decoding needs to happen to see that it's a branch, what the target is, etc. This could get a little more complicated if that gets done by the predecoder, but I'm choosing to ignore that for now. Variable length instructions: To handle variable length instructions in x86 and ARM, the predecoder now takes in the current PC by reference to the getExtMachInst function. It can modify the PC however it needs to (by setting NPC to be the PC + instruction length, for instance). This could be improved since the CPU doesn't know if the PC was modified and always has to write it back. ISA parser: To support the new API, all PC related operand types were removed from the parser and replaced with a PCState type. There are two warts on this implementation. First, as with all the other operand types, the PCState still has to have a valid operand type even though it doesn't use it. Second, using syntax like PCS.npc(target) doesn't work for two reasons, this looks like the syntax for operand type overriding, and the parser can't figure out if you're reading or writing. Instructions that use the PCS operand (which I've consistently called it) need to first read it into a local variable, manipulate it, and then write it back out. Return address stack: The return address stack needed a little extra help because, in the presence of branch delay slots, it has to merge together elements of the return PC and the call PC. To handle that, a buildRetPC utility function was added. There are basically only two versions in all the ISAs, but it didn't seem short enough to put into the generic ISA directory. Also, the branch predictor code in O3 and InOrder were adjusted so that they always store the PC of the actual call instruction in the RAS, not the next PC. If the call instruction is a microop, the next PC refers to the next microop in the same macroop which is probably not desirable. The buildRetPC function advances the PC intelligently to the next macroop (in an ISA specific way) so that that case works. Change in stats: There were no change in stats except in MIPS and SPARC in the O3 model. MIPS runs in about 9% fewer ticks. SPARC runs with 30%-50% fewer ticks, which could likely be improved further by setting call/return instruction flags and taking advantage of the RAS. TODO: Add != operators to the PCState classes, defined trivially to be !(a==b). Smooth out places where PCs are split apart, passed around, and put back together later. I think this might happen in SPARC's fault code. Add ISA specific constructors that allow setting PC elements without calling a bunch of accessors. Try to eliminate the need for the branching() function. Factor out Alpha's PAL mode pc bit into a separate flag field, and eliminate places where it's blindly masked out or tested in the PC. |
/gem5/src/cpu/o3/ | ||
H A D | SConscript | diff 9480:d059f8a95a42 Thu Jan 24 01:28:00 EST 2013 Nilay Vaish <nilay@cs.wisc.edu>, Timothy Jones <timothy.jones@cl.cam.ac.uk> branch predictor: move out of o3 and inorder cpus This patch moves the branch predictor files in the o3 and inorder directories to src/cpu/pred. This allows sharing the branch predictor across different cpu models. This patch was originally posted by Timothy Jones in July 2010 but never made it to the repository. |
H A D | scoreboard.hh | diff 7699:addb847910d2 Mon Oct 04 14:58:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> Alpha: Fix Alpha NumMiscArchRegs constant. Also add asserts in O3's Scoreboard class to catch bad indexes. |
/gem5/tests/configs/ | ||
H A D | realview-simple-atomic.py | 7735:a1a85250e897 Mon Nov 08 14:58:00 EST 2010 Ali Saidi <Ali.Saidi@ARM.com> ARM: Add full-system regressions |
H A D | o3-timing-ruby.py | diff 6870:5707ef3691b5 Mon Jan 25 12:51:00 EST 2010 Derek Hower <drh5@cs.wisc.edu> config: changed default ruby config file for regression |
H A D | realview-simple-timing.py | 7735:a1a85250e897 Mon Nov 08 14:58:00 EST 2010 Ali Saidi <Ali.Saidi@ARM.com> ARM: Add full-system regressions |
H A D | tsunami-o3-dual.py | diff 6978:ab05e20dc4a7 Tue Feb 23 12:34:00 EST 2010 Lisa Hsu <Lisa.Hsu@amd.com> cache: Make caches sharing aware and add occupancy stats. On the config end, if a shared L2 is created for the system, it is parameterized to have n sharers as defined by option.num_cpus. In addition to making the cache sharing aware so that discriminating tag policies can make use of context_ids to make decisions, I added an occupancy AverageStat and an occ % stat to each cache so that you could know which contexts are occupying how much cache on average, both in terms of blocks and percentage. Note that since devices have context_id -1, having an array of occ stats that correspond to each context_id will break here, so in FS mode I add an extra bucket for device blocks. This bucket is explicitly not added in SE mode in order to not only avoid ugliness in the stats.txt file, but to avoid broken stats (some formulas break when a bucket is 0). |
/gem5/src/kern/linux/ | ||
H A D | events.cc | diff 7676:92274350b953 Fri Sep 10 17:58:00 EDT 2010 Nathan Binkert <nate@binkert.org> style: fix sorting of includes and whitespace in some files |
/gem5/src/arch/sparc/linux/ | ||
H A D | process.hh | diff 7741:340b6f01d69b Thu Nov 11 05:03:00 EST 2010 Gabe Black <gblack@eecs.umich.edu> SPARC: Clean up some historical style issues. |
/gem5/src/arch/alpha/ | ||
H A D | faults.hh | diff 7678:f19b6a3a8cec Mon Sep 13 22:26:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> Faults: Pass the StaticInst involved, if any, to a Fault's invoke method. Also move the "Fault" reference counted pointer type into a separate file, sim/fault.hh. It would be better to name this less similarly to sim/faults.hh to reduce confusion, but fault.hh matches the name of the type. We could change Fault to FaultPtr to match other pointer types, and then changing the name of the file would make more sense. |
H A D | locked_mem.hh | diff 7783:9b880b40ac10 Tue Dec 07 19:19:00 EST 2010 Giacomo Gabrielli <Giacomo.Gabrielli@arm.com> O3: Make all instructions that write a misc. register not perform the write until commit. ARM instructions updating cumulative flags (ARM FP exceptions and saturation flags) are not serialized. Added aliases for ARM FP exceptions and saturation flags in FPSCR. Removed write accesses to the FP condition codes for most ARM VFP instructions: only VCMP and VCMPE instructions update the FP condition codes. Removed a potential cause of seg. faults in the O3 model for NEON memory macro-ops (ARM). |
H A D | process.hh | diff 7532:3f6413fc37a2 Tue Aug 17 08:17:00 EDT 2010 Steve Reinhardt <steve.reinhardt@amd.com> sim: revamp unserialization procedure Replace direct call to unserialize() on each SimObject with a pair of calls for better control over initialization in both ckpt and non-ckpt cases. If restoring from a checkpoint, loadState(ckpt) is called on each SimObject. The default implementation simply calls unserialize() if there is a corresponding checkpoint section, so we get backward compatibility for existing objects. However, objects can override loadState() to get other behaviors, e.g., doing other programmed initializations after unserialize(), or complaining if no checkpoint section is found. (Note that the default warning for a missing checkpoint section is now gone.) If not restoring from a checkpoint, we call the new initState() method on each SimObject instead. This provides a hook for state initializations that are only required when *not* restoring from a checkpoint. Given this new framework, do some cleanup of LiveProcess subclasses and X86System, which were (in some cases) emulating initState() behavior in startup via a local flag or (in other cases) erroneously doing initializations in startup() that clobbered state loaded earlier by unserialize(). |
/gem5/src/base/ | ||
H A D | random.cc | diff 7575:0002812cefe5 Mon Aug 23 12:18:00 EDT 2010 Ali Saidi <Ali.Saidi@ARM.com> BASE: Fix genrand to generate both 0s and 1s when max equals one. previously was only generating 0s. |
/gem5/src/arch/mips/isa/formats/ | ||
H A D | util.isa | diff 7045:e21fe6a62b1c Tue Mar 23 11:50:00 EDT 2010 Steve Reinhardt <steve.reinhardt@amd.com> cpu: fix exec tracing memory corruption bug Accessing traceData (to call setAddress() and/or setData()) after initiating a timing translation was causing crashes, since a failed translation could delete the traceData object before returning. It turns out that there was never a need to access traceData after initiating the translation, as the traced data was always available earlier; this ordering was merely historical. Furthermore, traceData->setAddress() and traceData->setData() were being called both from the CPU model and the ISA definition, often redundantly. This patch standardizes all setAddress and setData calls for memory instructions to be in the CPU models and not in the ISA definition. It also moves those calls above the translation calls to eliminate the crashes. |
/gem5/ext/libelf/ | ||
H A D | SConscript | diff 7739:f97a5f4d0879 Tue Nov 09 14:03:00 EST 2010 Gabe Black <gblack@eecs.umich.edu> scons: Work around for old versions of scons mistaking strings for sequences. |
/gem5/src/arch/power/insts/ | ||
H A D | static_inst.hh | diff 7720:65d338a8dba4 Sun Oct 31 03:07:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> ISA,CPU,etc: Create an ISA defined PC type that abstracts out ISA behaviors. This change is a low level and pervasive reorganization of how PCs are managed in M5. Back when Alpha was the only ISA, there were only 2 PCs to worry about, the PC and the NPC, and the lsb of the PC signaled whether or not you were in PAL mode. As other ISAs were added, we had to add an NNPC, micro PC and next micropc, x86 and ARM introduced variable length instruction sets, and ARM started to keep track of mode bits in the PC. Each CPU model handled PCs in its own custom way that needed to be updated individually to handle the new dimensions of variability, or, in the case of ARMs mode-bit-in-the-pc hack, the complexity could be hidden in the ISA at the ISA implementation's expense. Areas like the branch predictor hadn't been updated to handle branch delay slots or micropcs, and it turns out that had introduced a significant (10s of percent) performance bug in SPARC and to a lesser extend MIPS. Rather than perpetuate the problem by reworking O3 again to handle the PC features needed by x86, this change was introduced to rework PC handling in a more modular, transparent, and hopefully efficient way. PC type: Rather than having the superset of all possible elements of PC state declared in each of the CPU models, each ISA defines its own PCState type which has exactly the elements it needs. A cross product of canned PCState classes are defined in the new "generic" ISA directory for ISAs with/without delay slots and microcode. These are either typedef-ed or subclassed by each ISA. To read or write this structure through a *Context, you use the new pcState() accessor which reads or writes depending on whether it has an argument. If you just want the address of the current or next instruction or the current micro PC, you can get those through read-only accessors on either the PCState type or the *Contexts. These are instAddr(), nextInstAddr(), and microPC(). Note the move away from readPC. That name is ambiguous since it's not clear whether or not it should be the actual address to fetch from, or if it should have extra bits in it like the PAL mode bit. Each class is free to define its own functions to get at whatever values it needs however it needs to to be used in ISA specific code. Eventually Alpha's PAL mode bit could be moved out of the PC and into a separate field like ARM. These types can be reset to a particular pc (where npc = pc + sizeof(MachInst), nnpc = npc + sizeof(MachInst), upc = 0, nupc = 1 as appropriate), printed, serialized, and compared. There is a branching() function which encapsulates code in the CPU models that checked if an instruction branched or not. Exactly what that means in the context of branch delay slots which can skip an instruction when not taken is ambiguous, and ideally this function and its uses can be eliminated. PCStates also generally know how to advance themselves in various ways depending on if they point at an instruction, a microop, or the last microop of a macroop. More on that later. Ideally, accessing all the PCs at once when setting them will improve performance of M5 even though more data needs to be moved around. This is because often all the PCs need to be manipulated together, and by getting them all at once you avoid multiple function calls. Also, the PCs of a particular thread will have spatial locality in the cache. Previously they were grouped by element in arrays which spread out accesses. Advancing the PC: The PCs were previously managed entirely by the CPU which had to know about PC semantics, try to figure out which dimension to increment the PC in, what to set NPC/NNPC, etc. These decisions are best left to the ISA in conjunction with the PC type itself. Because most of the information about how to increment the PC (mainly what type of instruction it refers to) is contained in the instruction object, a new advancePC virtual function was added to the StaticInst class. Subclasses provide an implementation that moves around the right element of the PC with a minimal amount of decision making. In ISAs like Alpha, the instructions always simply assign NPC to PC without having to worry about micropcs, nnpcs, etc. The added cost of a virtual function call should be outweighed by not having to figure out as much about what to do with the PCs and mucking around with the extra elements. One drawback of making the StaticInsts advance the PC is that you have to actually have one to advance the PC. This would, superficially, seem to require decoding an instruction before fetch could advance. This is, as far as I can tell, realistic. fetch would advance through memory addresses, not PCs, perhaps predicting new memory addresses using existing ones. More sophisticated decisions about control flow would be made later on, after the instruction was decoded, and handed back to fetch. If branching needs to happen, some amount of decoding needs to happen to see that it's a branch, what the target is, etc. This could get a little more complicated if that gets done by the predecoder, but I'm choosing to ignore that for now. Variable length instructions: To handle variable length instructions in x86 and ARM, the predecoder now takes in the current PC by reference to the getExtMachInst function. It can modify the PC however it needs to (by setting NPC to be the PC + instruction length, for instance). This could be improved since the CPU doesn't know if the PC was modified and always has to write it back. ISA parser: To support the new API, all PC related operand types were removed from the parser and replaced with a PCState type. There are two warts on this implementation. First, as with all the other operand types, the PCState still has to have a valid operand type even though it doesn't use it. Second, using syntax like PCS.npc(target) doesn't work for two reasons, this looks like the syntax for operand type overriding, and the parser can't figure out if you're reading or writing. Instructions that use the PCS operand (which I've consistently called it) need to first read it into a local variable, manipulate it, and then write it back out. Return address stack: The return address stack needed a little extra help because, in the presence of branch delay slots, it has to merge together elements of the return PC and the call PC. To handle that, a buildRetPC utility function was added. There are basically only two versions in all the ISAs, but it didn't seem short enough to put into the generic ISA directory. Also, the branch predictor code in O3 and InOrder were adjusted so that they always store the PC of the actual call instruction in the RAS, not the next PC. If the call instruction is a microop, the next PC refers to the next microop in the same macroop which is probably not desirable. The buildRetPC function advances the PC intelligently to the next macroop (in an ISA specific way) so that that case works. Change in stats: There were no change in stats except in MIPS and SPARC in the O3 model. MIPS runs in about 9% fewer ticks. SPARC runs with 30%-50% fewer ticks, which could likely be improved further by setting call/return instruction flags and taking advantage of the RAS. TODO: Add != operators to the PCState classes, defined trivially to be !(a==b). Smooth out places where PCs are split apart, passed around, and put back together later. I think this might happen in SPARC's fault code. Add ISA specific constructors that allow setting PC elements without calling a bunch of accessors. Try to eliminate the need for the branching() function. Factor out Alpha's PAL mode pc bit into a separate flag field, and eliminate places where it's blindly masked out or tested in the PC. |
/gem5/src/arch/power/isa/formats/ | ||
H A D | unknown.isa | diff 7720:65d338a8dba4 Sun Oct 31 03:07:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> ISA,CPU,etc: Create an ISA defined PC type that abstracts out ISA behaviors. This change is a low level and pervasive reorganization of how PCs are managed in M5. Back when Alpha was the only ISA, there were only 2 PCs to worry about, the PC and the NPC, and the lsb of the PC signaled whether or not you were in PAL mode. As other ISAs were added, we had to add an NNPC, micro PC and next micropc, x86 and ARM introduced variable length instruction sets, and ARM started to keep track of mode bits in the PC. Each CPU model handled PCs in its own custom way that needed to be updated individually to handle the new dimensions of variability, or, in the case of ARMs mode-bit-in-the-pc hack, the complexity could be hidden in the ISA at the ISA implementation's expense. Areas like the branch predictor hadn't been updated to handle branch delay slots or micropcs, and it turns out that had introduced a significant (10s of percent) performance bug in SPARC and to a lesser extend MIPS. Rather than perpetuate the problem by reworking O3 again to handle the PC features needed by x86, this change was introduced to rework PC handling in a more modular, transparent, and hopefully efficient way. PC type: Rather than having the superset of all possible elements of PC state declared in each of the CPU models, each ISA defines its own PCState type which has exactly the elements it needs. A cross product of canned PCState classes are defined in the new "generic" ISA directory for ISAs with/without delay slots and microcode. These are either typedef-ed or subclassed by each ISA. To read or write this structure through a *Context, you use the new pcState() accessor which reads or writes depending on whether it has an argument. If you just want the address of the current or next instruction or the current micro PC, you can get those through read-only accessors on either the PCState type or the *Contexts. These are instAddr(), nextInstAddr(), and microPC(). Note the move away from readPC. That name is ambiguous since it's not clear whether or not it should be the actual address to fetch from, or if it should have extra bits in it like the PAL mode bit. Each class is free to define its own functions to get at whatever values it needs however it needs to to be used in ISA specific code. Eventually Alpha's PAL mode bit could be moved out of the PC and into a separate field like ARM. These types can be reset to a particular pc (where npc = pc + sizeof(MachInst), nnpc = npc + sizeof(MachInst), upc = 0, nupc = 1 as appropriate), printed, serialized, and compared. There is a branching() function which encapsulates code in the CPU models that checked if an instruction branched or not. Exactly what that means in the context of branch delay slots which can skip an instruction when not taken is ambiguous, and ideally this function and its uses can be eliminated. PCStates also generally know how to advance themselves in various ways depending on if they point at an instruction, a microop, or the last microop of a macroop. More on that later. Ideally, accessing all the PCs at once when setting them will improve performance of M5 even though more data needs to be moved around. This is because often all the PCs need to be manipulated together, and by getting them all at once you avoid multiple function calls. Also, the PCs of a particular thread will have spatial locality in the cache. Previously they were grouped by element in arrays which spread out accesses. Advancing the PC: The PCs were previously managed entirely by the CPU which had to know about PC semantics, try to figure out which dimension to increment the PC in, what to set NPC/NNPC, etc. These decisions are best left to the ISA in conjunction with the PC type itself. Because most of the information about how to increment the PC (mainly what type of instruction it refers to) is contained in the instruction object, a new advancePC virtual function was added to the StaticInst class. Subclasses provide an implementation that moves around the right element of the PC with a minimal amount of decision making. In ISAs like Alpha, the instructions always simply assign NPC to PC without having to worry about micropcs, nnpcs, etc. The added cost of a virtual function call should be outweighed by not having to figure out as much about what to do with the PCs and mucking around with the extra elements. One drawback of making the StaticInsts advance the PC is that you have to actually have one to advance the PC. This would, superficially, seem to require decoding an instruction before fetch could advance. This is, as far as I can tell, realistic. fetch would advance through memory addresses, not PCs, perhaps predicting new memory addresses using existing ones. More sophisticated decisions about control flow would be made later on, after the instruction was decoded, and handed back to fetch. If branching needs to happen, some amount of decoding needs to happen to see that it's a branch, what the target is, etc. This could get a little more complicated if that gets done by the predecoder, but I'm choosing to ignore that for now. Variable length instructions: To handle variable length instructions in x86 and ARM, the predecoder now takes in the current PC by reference to the getExtMachInst function. It can modify the PC however it needs to (by setting NPC to be the PC + instruction length, for instance). This could be improved since the CPU doesn't know if the PC was modified and always has to write it back. ISA parser: To support the new API, all PC related operand types were removed from the parser and replaced with a PCState type. There are two warts on this implementation. First, as with all the other operand types, the PCState still has to have a valid operand type even though it doesn't use it. Second, using syntax like PCS.npc(target) doesn't work for two reasons, this looks like the syntax for operand type overriding, and the parser can't figure out if you're reading or writing. Instructions that use the PCS operand (which I've consistently called it) need to first read it into a local variable, manipulate it, and then write it back out. Return address stack: The return address stack needed a little extra help because, in the presence of branch delay slots, it has to merge together elements of the return PC and the call PC. To handle that, a buildRetPC utility function was added. There are basically only two versions in all the ISAs, but it didn't seem short enough to put into the generic ISA directory. Also, the branch predictor code in O3 and InOrder were adjusted so that they always store the PC of the actual call instruction in the RAS, not the next PC. If the call instruction is a microop, the next PC refers to the next microop in the same macroop which is probably not desirable. The buildRetPC function advances the PC intelligently to the next macroop (in an ISA specific way) so that that case works. Change in stats: There were no change in stats except in MIPS and SPARC in the O3 model. MIPS runs in about 9% fewer ticks. SPARC runs with 30%-50% fewer ticks, which could likely be improved further by setting call/return instruction flags and taking advantage of the RAS. TODO: Add != operators to the PCState classes, defined trivially to be !(a==b). Smooth out places where PCs are split apart, passed around, and put back together later. I think this might happen in SPARC's fault code. Add ISA specific constructors that allow setting PC elements without calling a bunch of accessors. Try to eliminate the need for the branching() function. Factor out Alpha's PAL mode pc bit into a separate flag field, and eliminate places where it's blindly masked out or tested in the PC. |
/gem5/src/mem/cache/ | ||
H A D | mshr_queue.hh | diff 7667:aa8fd8f6a495 Thu Sep 09 14:40:00 EDT 2010 Steve Reinhardt <steve.reinhardt@amd.com> cache: coherence protocol enhancements & bug fixes Allow lower-level caches (e.g., L2 or L3) to pass exclusive copies to higher levels (e.g., L1). This eliminates a lot of unnecessary upgrade transactions on read-write sequences to non-shared data. Also some cleanup of MSHR coherence handling and multiple bug fixes. |
H A D | mshr_queue.cc | diff 7667:aa8fd8f6a495 Thu Sep 09 14:40:00 EDT 2010 Steve Reinhardt <steve.reinhardt@amd.com> cache: coherence protocol enhancements & bug fixes Allow lower-level caches (e.g., L2 or L3) to pass exclusive copies to higher levels (e.g., L1). This eliminates a lot of unnecessary upgrade transactions on read-write sequences to non-shared data. Also some cleanup of MSHR coherence handling and multiple bug fixes. |
/gem5/configs/example/ | ||
H A D | ruby_direct_test.py | 7632:acf43d6bbc18 Tue Aug 24 03:07:00 EDT 2010 Brad Beckmann <Brad.Beckmann@amd.com> testers: move testers to a new directory This patch moves the testers to a new subdirectory under src/cpu and includes the necessary fixes to work with latest m5 initialization patches. |
/gem5/src/arch/mips/ | ||
H A D | isa.hh | diff 7678:f19b6a3a8cec Mon Sep 13 22:26:00 EDT 2010 Gabe Black <gblack@eecs.umich.edu> Faults: Pass the StaticInst involved, if any, to a Fault's invoke method. Also move the "Fault" reference counted pointer type into a separate file, sim/fault.hh. It would be better to name this less similarly to sim/faults.hh to reduce confusion, but fault.hh matches the name of the type. We could change Fault to FaultPtr to match other pointer types, and then changing the name of the file would make more sense. |
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