From: Suresh Siddha Date: Wed, 5 Sep 2007 12:32:48 +0000 (+0200) Subject: sched: fix MC/HT scheduler optimization, without breaking the FUZZ logic. X-Git-Tag: v2.6.23-rc6~15^2~7 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7fd0d2dde929ead79901e389e70dbfb3c6c06986;p=linux-2.6 sched: fix MC/HT scheduler optimization, without breaking the FUZZ logic. First fix the check if (*imbalance + SCHED_LOAD_SCALE_FUZZ < busiest_load_per_task) with this if (*imbalance < busiest_load_per_task) As the current check is always false for nice 0 tasks (as SCHED_LOAD_SCALE_FUZZ is same as busiest_load_per_task for nice 0 tasks). With the above change, imbalance was getting reset to 0 in the corner case condition, making the FUZZ logic fail. Fix it by not corrupting the imbalance and change the imbalance, only when it finds that the HT/MC optimization is needed. Signed-off-by: Suresh Siddha Signed-off-by: Ingo Molnar --- diff --git a/kernel/sched.c b/kernel/sched.c index b533d6db78..c8759ec6d8 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -2512,7 +2512,7 @@ group_next: * a think about bumping its value to force at least one task to be * moved */ - if (*imbalance + SCHED_LOAD_SCALE_FUZZ < busiest_load_per_task) { + if (*imbalance < busiest_load_per_task) { unsigned long tmp, pwr_now, pwr_move; unsigned int imbn; @@ -2564,10 +2564,8 @@ small_imbalance: pwr_move /= SCHED_LOAD_SCALE; /* Move if we gain throughput */ - if (pwr_move <= pwr_now) - goto out_balanced; - - *imbalance = busiest_load_per_task; + if (pwr_move > pwr_now) + *imbalance = busiest_load_per_task; } return busiest;