On 11/19/18 11:54 AM, Kyrill Tkachov wrote: > On 16/11/18 18:19, Pat Haugen wrote: >> On 11/8/18 6:10 AM, Kyrill Tkachov wrote: >>> The attached patch avoids that by making the alap calculation only >>> look at true dependencies. This shouldn't be too bad, since we use >>> INSN_PRIORITY as the final tie-breaker than that does take >>> anti-dependencies into account. >>> >>> This reduces the number of spills in the hot function from 436.cactusADM >>> by 14% on aarch64 at -O3 (and the number of instructions in general). >>> SPEC2017 shows a minor improvement on Cortex-A72 (about 0.1% overall). >>> Thanks to Wilco for the benchmarking. >> I tried the patch on PowerPC since it also uses SCHED_PRESSURE_MODEL >> algorithm. For CPU2006 only cactusADM had a noticeable difference, but I'm >> seeing a 5% degradation. Looking at the generated asm for function >> bench_staggeredleapfrog2_(), I see about a 1% increase in number of loads >> and stores generated and an extra 100 bytes allocated on the stack. >> >> -Pat >> > > This is a follow-up from > https://gcc.gnu.org/ml/gcc-patches/2018-11/msg01525.html > This version introduces an "artificial" property of the dependencies produced > in > sched-deps.c that is recorded when they are created due to > MAX_PENDING_LIST_LENGTH > and they are thus ignored in the model_analyze_insns ALAP calculation. > > This approach gives most of the benefits of the original patch [1] on aarch64. > I tried it on the cactusADM hot function (bench_staggeredleapfrog2_) on > powerpc64le-unknown-linux-gnu > with -O3 and found that the initial version proposed did indeed increase the > instruction count > and stack space. This version gives a small improvement on powerpc in terms > of instruction count > (number of st* instructions stays the same), so I'm hoping this version > addresses Pat's concerns. > Pat, could you please try this version out if you've got the chance? >
I tried the new verison on cactusADM, it's showing a 2% degradation. I've kicked off a full CPU2006 run just to see if any others are affected. -Pat
