From: Ingo Molnar Date: Thu, 29 May 2008 12:32:23 +0000 (+0200) Subject: sched: re-tune NUMA topologies X-Git-Tag: v2.6.26-rc5~40^2~1 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ea3f01f8afd3bc5daff915cc4ea5cc5ea9e7d427;p=linux-2.6 sched: re-tune NUMA topologies improve the sysbench ramp-up phase and its peak throughput on a 16way NUMA box, by turning on WAKE_AFFINE: tip/sched tip/sched+wake-affine ------------------------------------------------- 1: 700 830 +15.65% 2: 1465 1391 -5.28% 4: 3017 3105 +2.81% 8: 5100 6021 +15.30% 16: 10725 10745 +0.19% 32: 10135 10150 +0.16% 64: 9338 9240 -1.06% 128: 8599 8252 -4.21% 256: 8475 8144 -4.07% ------------------------------------------------- SUM: 57558 57882 +0.56% this change also improves lat_ctx from 6.69 usecs to 1.11 usec: $ ./lat_ctx -s 0 2 "size=0k ovr=1.19 2 1.11 $ ./lat_ctx -s 0 2 "size=0k ovr=1.22 2 6.69 in sysbench it's an overall win with some weakness at the lots-of-clients side. That happens because we now under-balance this workload a bit. To counter that effect, turn on NEWIDLE: wake-idle wake-idle+newidle ------------------------------------------------- 1: 830 834 +0.43% 2: 1391 1401 +0.65% 4: 3105 3091 -0.43% 8: 6021 6046 +0.42% 16: 10745 10736 -0.08% 32: 10150 10206 +0.55% 64: 9240 9533 +3.08% 128: 8252 8355 +1.24% 256: 8144 8384 +2.87% ------------------------------------------------- SUM: 57882 58591 +1.21% as a bonus this not only improves the many-clients case but also improves the (more important) rampup phase. sysbench is a workload that quickly breaks down if the scheduler over-balances, so since it showed an improvement under NEWIDLE this change is definitely good. --- diff --git a/include/linux/topology.h b/include/linux/topology.h index 4bb7074a2c..24f3d2282e 100644 --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -166,7 +166,9 @@ void arch_update_cpu_topology(void); .busy_idx = 3, \ .idle_idx = 3, \ .flags = SD_LOAD_BALANCE \ - | SD_SERIALIZE, \ + | SD_BALANCE_NEWIDLE \ + | SD_WAKE_AFFINE \ + | SD_SERIALIZE, \ .last_balance = jiffies, \ .balance_interval = 64, \ }