* [PATCH] percpu: add a schedule point in pcpu_balance_workfn()
@ 2018-02-23 16:12 Eric Dumazet
2018-02-23 16:53 ` Tejun Heo
0 siblings, 1 reply; 2+ messages in thread
From: Eric Dumazet @ 2018-02-23 16:12 UTC (permalink / raw)
To: Tejun Heo; +Cc: linux-kernel, netdev
From: Eric Dumazet <edumazet@google.com>
When a large BPF percpu map is destroyed, I have seen
pcpu_balance_workfn() holding cpu for hundreds of milliseconds.
On KASAN config and 112 hyperthreads, average time to destroy a chunk
is ~4 ms.
[ 2489.841376] destroy chunk 1 in 4148689 ns
...
[ 2490.093428] destroy chunk 32 in 4072718 ns
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
mm/percpu.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/mm/percpu.c b/mm/percpu.c
index 50e7fdf84055151d8c7e8bb220f7a73e96b7f3e4..d40dfb597ffce2656220257f0227219ab917135b 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1600,6 +1600,7 @@ static void pcpu_balance_workfn(struct work_struct *work)
spin_unlock_irq(&pcpu_lock);
}
pcpu_destroy_chunk(chunk);
+ cond_resched();
}
/*
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] percpu: add a schedule point in pcpu_balance_workfn()
2018-02-23 16:12 [PATCH] percpu: add a schedule point in pcpu_balance_workfn() Eric Dumazet
@ 2018-02-23 16:53 ` Tejun Heo
0 siblings, 0 replies; 2+ messages in thread
From: Tejun Heo @ 2018-02-23 16:53 UTC (permalink / raw)
To: Eric Dumazet; +Cc: linux-kernel, netdev
On Fri, Feb 23, 2018 at 08:12:42AM -0800, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@google.com>
>
> When a large BPF percpu map is destroyed, I have seen
> pcpu_balance_workfn() holding cpu for hundreds of milliseconds.
>
> On KASAN config and 112 hyperthreads, average time to destroy a chunk
> is ~4 ms.
>
> [ 2489.841376] destroy chunk 1 in 4148689 ns
> ...
> [ 2490.093428] destroy chunk 32 in 4072718 ns
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
Applied to percpu/for-4.16-fixes.
Thank, Eric.
--
tejun
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