> On Aug. 3, 2012, 10:53 a.m., Steve Reinhardt wrote: > > src/sim/clocked_object.hh, line 91 > > <http://reviews.gem5.org/r/1321/diff/2/?file=28275#file28275line91> > > > > Sorry not to be more clear. I meant that both lines 92 and 93 (the > > cycle and tick assignments) should be replaced. The line I provided was > > meant to come first and show how tick would need to be updated based on its > > current value. I was leaving the corresponding update of cycle as an > > exercise for the reader ;-). Actually at that point I was probably in my > > phase where I was hoping that we could eliminate cycle entirely. > > > > If we do keep cycle, it would be more like: > > > > CycleCount elapsedCycles = divCeil(curTick() - tick, clock); > > cycle += elapsedCycles; > > tick += elapsedCycles * clock; > > > >
I agree conceptually. However, it actually changes the regression as the rounding is slightly different. This is not a problem as such, but I would still like to keep it out of this patch. Agreed? - Andreas ----------------------------------------------------------- This is an automatically generated e-mail. To reply, visit: http://reviews.gem5.org/r/1321/#review3200 ----------------------------------------------------------- On Aug. 3, 2012, 4:54 a.m., Andreas Hansson wrote: > > ----------------------------------------------------------- > This is an automatically generated e-mail. To reply, visit: > http://reviews.gem5.org/r/1321/ > ----------------------------------------------------------- > > (Updated Aug. 3, 2012, 4:54 a.m.) > > > Review request for Default. > > > Description > ------- > > Changeset 9143:10fd4f94efa4 > --------------------------- > Clock: Rework clocks to avoid tick-to-cycle transformations > > This patch introduces the notion of a clock update function that aims > to avoid costly divisions when turning the current tick into a > cycle. Each clocked object advances a private (hidden) cycle member > and a tick member and uses these to implement functions for getting > the tick of the next cycle, or the tick of a cycle some time in the > future. > > In the different modules using the clocks, changes are made to avoid > counting in ticks only to later translate to cycles. There are a few > oddities in how the O3 and inorder CPU count idle cycles, as seen by a > few locations where a cycle is subtracted in the calculation. This is > done such that the regression does not change any stats, but should be > revisited in a future patch. > > Another, much needed, change that is not done as part of this patch is > to introduce a new typedef uint64_t Cycle to be able to at least hint > at the unit of the variables counting Ticks vs Cycles. This will be > done as a follow-up patch. > > As an additional follow up, the thread context still uses ticks for > the book keeping of last activate and last suspend and this should > probably also be changed into cycles as well. > > > Diffs > ----- > > src/arch/arm/table_walker.cc b4d0bdb52694 > src/arch/x86/mmapped_ipr.hh b4d0bdb52694 > src/cpu/base.cc b4d0bdb52694 > src/cpu/inorder/cpu.hh b4d0bdb52694 > src/cpu/inorder/cpu.cc b4d0bdb52694 > src/cpu/inorder/resource.cc b4d0bdb52694 > src/cpu/inorder/resource_pool.cc b4d0bdb52694 > src/cpu/o3/O3CPU.py b4d0bdb52694 > src/cpu/o3/commit.hh b4d0bdb52694 > src/cpu/o3/commit_impl.hh b4d0bdb52694 > src/cpu/o3/cpu.hh b4d0bdb52694 > src/cpu/o3/cpu.cc b4d0bdb52694 > src/cpu/o3/fetch_impl.hh b4d0bdb52694 > src/cpu/o3/inst_queue_impl.hh b4d0bdb52694 > src/cpu/o3/lsq_unit.hh b4d0bdb52694 > src/cpu/simple/atomic.cc b4d0bdb52694 > src/cpu/simple/timing.hh b4d0bdb52694 > src/cpu/simple/timing.cc b4d0bdb52694 > src/cpu/testers/memtest/memtest.cc b4d0bdb52694 > src/cpu/testers/networktest/networktest.cc b4d0bdb52694 > src/dev/arm/pl111.cc b4d0bdb52694 > src/dev/i8254xGBe.cc b4d0bdb52694 > src/dev/ns_gige.cc b4d0bdb52694 > src/sim/clocked_object.hh PRE-CREATION > > Diff: http://reviews.gem5.org/r/1321/diff/ > > > Testing > ------- > > util/regress all passing (disregarding t1000 and eio) > > A minor update. This change did improve performance. Running the > full regression, including a clean compile of all the ISAs went > down by 8%. Note that this includes the time for building as well. > > > Thanks, > > Andreas Hansson > > _______________________________________________ gem5-dev mailing list [email protected] http://m5sim.org/mailman/listinfo/gem5-dev
