sched: Improve latencies and throughput
Make the idle balancer more agressive, to improve a x264 encoding workload provided by Jason Garrett-Glaser: NEXT_BUDDY NO_LB_BIAS encoded 600 frames, 252.82 fps, 22096.60 kb/s encoded 600 frames, 250.69 fps, 22096.60 kb/s encoded 600 frames, 245.76 fps, 22096.60 kb/s NO_NEXT_BUDDY LB_BIAS encoded 600 frames, 344.44 fps, 22096.60 kb/s encoded 600 frames, 346.66 fps, 22096.60 kb/s encoded 600 frames, 352.59 fps, 22096.60 kb/s NO_NEXT_BUDDY NO_LB_BIAS encoded 600 frames, 425.75 fps, 22096.60 kb/s encoded 600 frames, 425.45 fps, 22096.60 kb/s encoded 600 frames, 422.49 fps, 22096.60 kb/s Peter pointed out that this is better done via newidle_idx, not via LB_BIAS, newidle balancing should look for where there is load _now_, not where there was load 2 ticks ago. Worst-case latencies are improved as well as no buddies means less vruntime spread. (as per prior lkml discussions) This change improves kbuild-peak parallelism as well. Reported-by: Jason Garrett-Glaser <darkshikari@gmail.com> Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1253011667.9128.16.camel@marge.simson.net> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Ingo Molnar

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@@ -116,14 +116,12 @@ extern unsigned long node_remap_size[];
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# define SD_CACHE_NICE_TRIES 1
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# define SD_IDLE_IDX 1
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# define SD_NEWIDLE_IDX 2
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# define SD_FORKEXEC_IDX 0
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#else
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# define SD_CACHE_NICE_TRIES 2
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# define SD_IDLE_IDX 2
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# define SD_NEWIDLE_IDX 2
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# define SD_FORKEXEC_IDX 1
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#endif
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@@ -137,7 +135,7 @@ extern unsigned long node_remap_size[];
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.cache_nice_tries = SD_CACHE_NICE_TRIES, \
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.busy_idx = 3, \
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.idle_idx = SD_IDLE_IDX, \
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.newidle_idx = SD_NEWIDLE_IDX, \
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.newidle_idx = 0, \
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.wake_idx = 0, \
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.forkexec_idx = SD_FORKEXEC_IDX, \
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\
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