Subject : oltp ~10% regression with 2.6.27-rc5 on stoakley machine Submitter : Lin Ming <ming.m.lin@intel.com> Date : 2008-09-04 7:06 References : http://marc.info/?l=linux-kernel&m=122051202202373&w=4 Handled-By : Peter Zijlstra <a.p.zijlstra@chello.nl> Handled-By : Gregory Haskins <ghaskins@novell.com> Handled-By : Ingo Molnar <mingo@elte.hu> This entry is being used for tracking a regression from 2.6.26. Please don't close it until the problem is fixed in the mainline.
References : http://marc.info/?t=122089704700005&r=1&w=4
Does it regress against .26? I can't seem to reproduce this with MySQL +sysbench on my quad, if anything .27-rc6 is faster than .26 Linux twins.programming.kicks-ass.net 2.6.26 #122 SMP PREEMPT Thu Sep 11 13:31:43 CEST 2008 x86_64 x86_64 x86_64 GNU/Linux 1: transactions: 52618 (876.97 per sec.) 2: transactions: 99682 (1661.36 per sec.) 4: transactions: 190681 (3177.96 per sec.) 8: transactions: 186881 (3114.58 per sec.) 16: transactions: 180133 (3002.02 per sec.) 32: transactions: 173474 (2890.97 per sec.) 64: transactions: 166760 (2778.86 per sec.) Linux twins.programming.kicks-ass.net 2.6.27-rc6 #123 SMP PREEMPT Thu Sep 11 14:02:45 CEST 2008 x86_64 x86_64 x86_64 GNU/Linux 1: transactions: 53475 (891.25 per sec.) 2: transactions: 100953 (1682.52 per sec.) 4: transactions: 192381 (3206.31 per sec.) 8: transactions: 187336 (3122.18 per sec.) 16: transactions: 180992 (3016.38 per sec.) 32: transactions: 172133 (2868.60 per sec.) 64: transactions: 168367 (2805.68 per sec.)
Yes, ~14% regression with 2.6.27-rc5 compared with 2.6.26
sched_switch trace of oltp in 2.6.27-rc4 http://myfreefilehosting.com/f/fc6c8eaacf_1.31MB sched_switch trace of oltp in 2.6.27-rc5 http://myfreefilehosting.com/f/a2f9aea1b0_0.42MB Compared the 2 trace files, you can find that (at most time), with 2.6.27-rc5, mysql switches to sysbench when it's going to sleep mysqld-3791 [07] 151.421836: 3791:120:R + 3803:120:S mysqld-3791 [07] 151.421876: 3791:120:S ==> 3803:120:R sysbench-3803 [07] 151.421878: 3803:120:R + 3791:120:S sysbench-3803 [07] 151.421887: 3803:120:S ==> 3791:120:R with 2.6.27-rc4, mysql switches to sysbench when it's still running mysqld-3674 [07] 95.960220: 3674:120:R + 3687:120:S mysqld-3674 [07] 95.960220: 3674:120:R ==> 3687:120:R sysbench-3687 [07] 95.960220: 3687:120:S ==> 3674:120:R So with 2.6.27-rc5, sysbench wakes up mysql and then switches to it (mysql is in sleep state) With 2.6.27-rc4, sysbench switches to mysql, no need to wake up it (mysql is still in running state)
Patch : http://marc.info/?l=linux-kernel&m=122194673932703&w=4
kernel peformance ----------------------------------- 27-rc4 100% 27-rc5 89.6% 27-rc5+peter's patch 94.5%
This issue appears to have been fixed. Closing.