[SRU,Bionic] sched/fair: Fix -Wunused-but-set-variable warnings
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Message ID 5fe102d92a12afcc126dd14253af68cfca4ab087.1571648800.git.juergh@canonical.com
State New
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Series
  • [SRU,Bionic] sched/fair: Fix -Wunused-but-set-variable warnings
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Commit Message

Juerg Haefliger Oct. 21, 2019, 9:06 a.m. UTC
From: Qian Cai <cai@lca.pw>

BugLink: https://bugs.launchpad.net/bugs/1832151

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.

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: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: pauld@redhat.com
Fixes: de53fd7aedb1 ("sched/fair: Fix low cpu usage with high throttling by removing expiration of cpu-local slices")
Link: https://lkml.kernel.org/r/1566326455-8038-1-git-send-email-cai@lca.pw
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(backported from commit 763a9ec06c409dcde2a761aac4bb83ff3938e0b3)
[juergh: Dropped modifications of start_cfs_bandwidth() (not applicable for
 Bionic 4.15).]
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
---
 kernel/sched/fair.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

Comments

Kleber Souza Oct. 21, 2019, 2:55 p.m. UTC | #1
On 10/21/19 11:06 AM, Juerg Haefliger wrote:
> From: Qian Cai <cai@lca.pw>
> 
> BugLink: https://bugs.launchpad.net/bugs/1832151
> 
> 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.
> 
> 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: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: pauld@redhat.com
> Fixes: de53fd7aedb1 ("sched/fair: Fix low cpu usage with high throttling by removing expiration of cpu-local slices")
> Link: https://lkml.kernel.org/r/1566326455-8038-1-git-send-email-cai@lca.pw
> Signed-off-by: Ingo Molnar <mingo@kernel.org>
> (backported from commit 763a9ec06c409dcde2a761aac4bb83ff3938e0b3)
> [juergh: Dropped modifications of start_cfs_bandwidth() (not applicable for
>  Bionic 4.15).]
> Signed-off-by: Juerg Haefliger <juergh@canonical.com>

Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

> ---
>  kernel/sched/fair.c | 15 +++++----------
>  1 file changed, 5 insertions(+), 10 deletions(-)
> 
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 7c797c8c8071..6c5766f9e924 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -4429,21 +4429,16 @@ static inline u64 sched_cfs_bandwidth_slice(void)
>  }
>  
>  /*
> - * 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)
>
Khaled Elmously Oct. 21, 2019, 4:20 p.m. UTC | #2
On 2019-10-21 11:06:40 , Juerg Haefliger wrote:
> From: Qian Cai <cai@lca.pw>
> 
> BugLink: https://bugs.launchpad.net/bugs/1832151
> 
> 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.
> 
> 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: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: pauld@redhat.com
> Fixes: de53fd7aedb1 ("sched/fair: Fix low cpu usage with high throttling by removing expiration of cpu-local slices")
> Link: https://lkml.kernel.org/r/1566326455-8038-1-git-send-email-cai@lca.pw
> Signed-off-by: Ingo Molnar <mingo@kernel.org>
> (backported from commit 763a9ec06c409dcde2a761aac4bb83ff3938e0b3)
> [juergh: Dropped modifications of start_cfs_bandwidth() (not applicable for
>  Bionic 4.15).]
> Signed-off-by: Juerg Haefliger <juergh@canonical.com>
> ---
>  kernel/sched/fair.c | 15 +++++----------
>  1 file changed, 5 insertions(+), 10 deletions(-)
> 
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 7c797c8c8071..6c5766f9e924 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -4429,21 +4429,16 @@ static inline u64 sched_cfs_bandwidth_slice(void)
>  }
>  
>  /*
> - * 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)
> -- 
> 2.20.1
> 
>

Thanks for catching that Juerg!
 
Acked-by: Khalid Elmously <khalid.elmously@canonical.com>

Patch
diff mbox series

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7c797c8c8071..6c5766f9e924 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4429,21 +4429,16 @@  static inline u64 sched_cfs_bandwidth_slice(void)
 }
 
 /*
- * 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)