> > > > > > > $ cat strace_c.sh > > > strace -tt -p $1 -c -o result_$1.log & > > > sleep $2 > > > pid=$(pidof strace) > > > kill $pid > > > cat result_$1.log > > > > > > Before appling this change: > > > $ ./strace_c.sh 10528 30 > > > % time seconds usecs/call calls errors syscall > > > ------ ----------- ----------- --------- --------- ---------------- > > > 93.87 0.119070 30 4000 ppoll > > > 3.27 0.004148 2 2038 ioctl > > > 2.66 0.003370 2 2014 futex > > > 0.09 0.000113 1 106 read > > > 0.09 0.000109 1 104 io_getevents > > > 0.02 0.000029 1 30 poll > > > 0.00 0.000000 0 1 write > > > ------ ----------- ----------- --------- --------- ---------------- > > > 100.00 0.126839 8293 total > > > > > > After appling the change: > > > $ ./strace_c.sh 23829 30 > > > % time seconds usecs/call calls errors syscall > > > ------ ----------- ----------- --------- --------- ---------------- > > > 92.86 0.067441 16 4094 ppoll > > > 4.85 0.003522 2 2136 ioctl > > > 1.17 0.000850 4 189 futex > > > 0.54 0.000395 2 202 read > > > 0.52 0.000379 2 202 io_getevents > > > 0.05 0.000037 1 30 poll > > > ------ ----------- ----------- --------- --------- ---------------- > > > 100.00 0.072624 6853 total > > > > > > The futex call number decreases ~90.6% on an idle windows 7 guest. > > > > These are the same figures as from v1 -- it would be interesting > > to check whether the additional locking that v2 adds has affected > > the results. > > > Oh, yes. the futex number of v2 don't decline compared too much to v1 because > it > takes the BQL before raising the outbound IRQ line now. > > Before applying v2: > # ./strace_c.sh 8776 30 > % time seconds usecs/call calls errors syscall > ------ ----------- ----------- --------- --------- ---------------- > 78.01 0.164188 26 6436 ppoll > 8.39 0.017650 5 3700 39 futex > 7.68 0.016157 6 2758 ioctl > 5.48 0.011530 3 4586 1113 read > 0.30 0.000640 20 32 io_submit > 0.15 0.000317 4 89 write > ------ ----------- ----------- --------- --------- ---------------- > 100.00 0.210482 17601 1152 total > > After applying v2: > # ./strace_c.sh 15968 30 > % time seconds usecs/call calls errors syscall > ------ ----------- ----------- --------- --------- ---------------- > 78.28 0.171117 27 6272 ppoll > 8.50 0.018571 5 3663 21 futex > 7.76 0.016973 6 2732 ioctl > 4.85 0.010597 3 4115 853 read > 0.31 0.000672 11 63 io_submit > 0.30 0.000659 4 180 write > ------ ----------- ----------- --------- --------- ---------------- > 100.00 0.218589 17025 874 total > > > Does the patch improve performance in a more interesting use > > case than "the guest is just idle" ? > > > I think so, after all, the scope of the locking is reduced . > Besides this, can we optimize the rtc timer to avoid to hold BQL > by separate threads? > Hi Peter, Paolo
I tested PCMark 8 (https://www.futuremark.com/benchmarks/pcmark) in win7 guest and got the below results: Guest: 2U2G Before applying v2: Your Work 2.0 score: 2000 Web Browsing - JunglePin 0.334s Web Browsing - Amazonia 0.132s Writing 3.59s Spreadsheet 70.13s Video Chat v2/Video Chat playback 1 v2 22.8 fps Video Chat v2/Video Chat encoding v2 307.0 ms Benchmark duration 1h 35min 46s After applying v2: Your Work 2.0 score: 2040 Web Browsing - JunglePin 0.345s Web Browsing - Amazonia 0.132s Writing 3.56s Spreadsheet 67.83s Video Chat v2/Video Chat playback 1 v2 28.7 fps Video Chat v2/Video Chat encoding v2 324.7 ms Benchmark duration 1h 32min 5s Test results show that optimization is very effective in stressful situations. Thanks, -Gonglei