Messages in this thread Patch in this message | | | Date | Tue, 3 Sep 2019 16:15:54 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH -next v2] sched/fair: fix -Wunused-but-set-variable warnings |
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On Tue, Sep 03, 2019 at 09:03:26AM -0400, Qian Cai wrote: > Ingo or Peter, please take a look at this trivial patch. Still see the warning > in linux-next every day. > > On Tue, 2019-08-20 at 14:40 -0400, Qian Cai wrote: > > The linux-next commit "sched/fair: Fix low cpu usage with high > > throttling by removing expiration of cpu-local slices" [1] introduced a > > few compilation warnings, > > > > kernel/sched/fair.c: In function '__refill_cfs_bandwidth_runtime': > > kernel/sched/fair.c:4365:6: warning: variable 'now' set but not used > > [-Wunused-but-set-variable] > > kernel/sched/fair.c: In function 'start_cfs_bandwidth': > > kernel/sched/fair.c:4992:6: warning: variable 'overrun' set but not used > > [-Wunused-but-set-variable] > > > > Also, __refill_cfs_bandwidth_runtime() does no longer update the > > expiration time, so fix the comments accordingly. > > > > [1] https://lore.kernel.org/lkml/1558121424-2914-1-git-send-email-chiluk+linux > > @indeed.com/ > > > > Signed-off-by: Qian Cai <cai@lca.pw>
Rewrote the Changelog like so:
--- Subject: sched/fair: Fix -Wunused-but-set-variable warnings From: Qian Cai <cai@lca.pw> Date: Tue, 20 Aug 2019 14:40:55 -0400
Commit de53fd7aedb1 ("sched/fair: Fix low cpu usage with high throttling by removing expiration of cpu-local slices") introduced a few compilation warnings:
kernel/sched/fair.c: In function '__refill_cfs_bandwidth_runtime': kernel/sched/fair.c:4365:6: warning: variable 'now' set but not used [-Wunused-but-set-variable] kernel/sched/fair.c: In function 'start_cfs_bandwidth': kernel/sched/fair.c:4992:6: warning: variable 'overrun' set but not used [-Wunused-but-set-variable]
Also, __refill_cfs_bandwidth_runtime() does no longer update the expiration time, so fix the comments accordingly.
Fixes: de53fd7aedb1 ("sched/fair: Fix low cpu usage with high throttling by removing expiration of cpu-local slices") Signed-off-by: Qian Cai <cai@lca.pw> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Ben Segall <bsegall@google.com> Reviewed-by: Dave Chiluk <chiluk+linux@indeed.com> Cc: mingo@redhat.com Cc: pauld@redhat.com Link: https://lkml.kernel.org/r/1566326455-8038-1-git-send-email-cai@lca.pw --- kernel/sched/fair.c | 19 ++++++------------- 1 file changed, 6 insertions(+), 13 deletions(-)
--- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4386,21 +4386,16 @@ static inline u64 sched_cfs_bandwidth_sl } /* - * Replenish runtime according to assigned quota and update expiration time. - * We use sched_clock_cpu directly instead of rq->clock to avoid adding - * additional synchronization around rq->lock. + * Replenish runtime according to assigned quota. We use sched_clock_cpu + * directly instead of rq->clock to avoid adding additional synchronization + * around rq->lock. * * requires cfs_b->lock */ void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b) { - u64 now; - - if (cfs_b->quota == RUNTIME_INF) - return; - - now = sched_clock_cpu(smp_processor_id()); - cfs_b->runtime = cfs_b->quota; + if (cfs_b->quota != RUNTIME_INF) + cfs_b->runtime = cfs_b->quota; } static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg) @@ -5021,15 +5016,13 @@ static void init_cfs_rq_runtime(struct c void start_cfs_bandwidth(struct cfs_bandwidth *cfs_b) { - u64 overrun; - lockdep_assert_held(&cfs_b->lock); if (cfs_b->period_active) return; cfs_b->period_active = 1; - overrun = hrtimer_forward_now(&cfs_b->period_timer, cfs_b->period); + hrtimer_forward_now(&cfs_b->period_timer, cfs_b->period); hrtimer_start_expires(&cfs_b->period_timer, HRTIMER_MODE_ABS_PINNED); }
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