Messages in this thread Patch in this message | | | Date | Mon, 19 Dec 2016 23:40:14 +0100 | From | Samuel Thibault <> | Subject | [PATCH] sched/fair: fix calc_cfs_shares fixed point arithmetics |
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2159197d6677 ("sched/core: Enable increased load resolution on 64-bit kernels")
exposed yet another miscalculation in calc_cfs_shares: MIN_SHARES is unscaled, and must thus be scaled before being manipulated against "shares" amounts.
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: stable@vger.kernel.org Fixes: 2159197d6677 ("sched/core: Enable increased load resolution on 64-bit kernels")
--- This should be backported to 4.7 and 4.8 to fix scheduling priorities miscalculations
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 6559d19..be84f72 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2657,8 +2657,8 @@ static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg) if (tg_weight) shares /= tg_weight; - if (shares < MIN_SHARES) - shares = MIN_SHARES; + if (shares < scale_load(MIN_SHARES)) + shares = scale_load(MIN_SHARES); if (shares > tg->shares) shares = tg->shares;
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