On Thu 11-04-13 10:43:46, Michal Hocko wrote: > Hi, > I have retested kbuild test on a bare HW (8CPUs, 1GB RAM limited by > mem=1G, 2GB swap partition). There are 2 groups (A, B) without any hard > limit and group A has soft limit set to 700M (to have 70% of available > memory). Build starts after fresh boot by extracting sources and > make -j4 vmlinux. > Each group works on a separate source tree. I have repeated the test 3 > times: > > First some data as returned by /usr/bin/time -v: > * Patched: > A: > User time (seconds): 1133.06 > User time (seconds): 1132.84 > User time (seconds): 1135.37 > Avg: 1133.76 > System time (seconds): 258.02 > System time (seconds): 259.33 > System time (seconds): 258.83 > Avg: 258.73 > Elapsed (wall clock) time (h:mm:ss or m:ss): 8:57.55 > Elapsed (wall clock) time (h:mm:ss or m:ss): 8:55.68 > Elapsed (wall clock) time (h:mm:ss or m:ss): 8:50.96 > Avg: 08:54.73 > > B: > User time (seconds): 1149.22 > User time (seconds): 1153.98 > User time (seconds): 1150.37 > Avg: 1151.19 (101.5% of A) > System time (seconds): 262.13 > System time (seconds): 263.31 > System time (seconds): 260.84 > Avg: 262.09 (101.3% of A) > Elapsed (wall clock) time (h:mm:ss or m:ss): 10:13.37 > Elapsed (wall clock) time (h:mm:ss or m:ss): 10:17.15 > Elapsed (wall clock) time (h:mm:ss or m:ss): 10:05.23 > Avg: 10:11.92 (114.4% of A) > > * Base: > A: > User time (seconds): 1132.58 > User time (seconds): 1140.63 > User time (seconds): 1135.68 > avg: 1136.30 (100.2% of A - patched) > System time (seconds): 264.88 > System time (seconds): 263.54 > System time (seconds): 261.99 > avg: 263.47 (101.8 of A - patched) > Elapsed (wall clock) time (h:mm:ss or m:ss): 9:48.54 > Elapsed (wall clock) time (h:mm:ss or m:ss): 9:50.44 > Elapsed (wall clock) time (h:mm:ss or m:ss): 9:44.28 > avg: 09:47.75 (109.9% of A - patched) > > B: > User time (seconds): 1138.32 > User time (seconds): 1135.70 > User time (seconds): 1136.80 > avg: 1136.94 (100.2% of A - patched) > > System time (seconds): 261.56 > System time (seconds): 262.10 > System time (seconds): 262.24 > avg: 261.97 (100% of A - patched) > Elapsed (wall clock) time (h:mm:ss or m:ss): 9:39.17 > Elapsed (wall clock) time (h:mm:ss or m:ss): 9:46.95 > Elapsed (wall clock) time (h:mm:ss or m:ss): 9:44.73 > avg: 09:47.75 (109.1% of A - patched) > > While for the patched kernel soft limit helped to protect A's working > set so it was faster (14% in the total time) than B without any limits. > The unpatched kernel has treated them more or less equally regardless > the softlimit setting. > > If we compare patched and base kernels numbers then the overall > situation improved slightly (A+B Elapsed time is 2% smaller) with the > patched kernel which was quite surprising for me. Maybe a side effect of > priority-0 soft reclaim in the base kernel. > > As the variance between runs wasn't very high I have focused on the first > run for the memory usage and reclaim statistics comparisons between the > base and patched kernels. > > * Patched: > pgscan_direct_dma32 252408 > pgscan_kswapd_dma32 988928 > pgsteal_direct_dma32 63565 > pgsteal_kswapd_dma32 905223 > > * Base: > pgscan_direct_dma32 97310 (38% of patched) > pgscan_kswapd_dma32 1702971 (172%) > pgsteal_direct_dma32 83377 (131%) > pgsteal_kswapd_dma32 1534616 (169.5%) > > So it seems that we scanned much more on the patched kernel during the > direct reclaim but we have reclaimed less nevertheless. This is most > probably because there is a bigger pressure on B's LRU and we encounter > more dirty pages so more pages are scanned in the end. In sum we scanned > and reclaimed less (by 45% resp. 67%) though. > I have moved graphs to http://labs.suse.cz/mhocko/soft_limit_rework/kbuild/700-softlimit/kbuild because I am doing tests with other soft limits and also other types of tests. Sorry about that. > You can find some graphs at: > - http://labs.suse.cz/mhocko/soft_limit_rework/base-usage.png > - http://labs.suse.cz/mhocko/soft_limit_rework/patched-usage.png > > Per group charges over time. > > - http://labs.suse.cz/mhocko/soft_limit_rework/base-usage-histogram.png > - http://labs.suse.cz/mhocko/soft_limit_rework/patched-usage-histogram.png > > Same here but in the histogram form to see the main tendencies. > > - http://labs.suse.cz/mhocko/soft_limit_rework/pgscan.png > - http://labs.suse.cz/mhocko/soft_limit_rework/pgsteal.png > > Scanning and reclaiming activity comparision between the base and the > patched kernel. > -- > Michal Hocko > SUSE Labs > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@xxxxxxxxx. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
