[PATCH] delayacct: add memory reclaim delay in get_page_from_freelist

[PATCH] delayacct: add memory reclaim delay in get_page_from_freelist

[liwenyu]

The current memory reclaim delay statistics only count the direct memory
reclaim of the task in do_try_to_free_pages(). In systems with NUMA
open, some tasks occasionally experience slower response times, but the
total count of reclaim does not increase, using ftrace can show that
node_reclaim has occurred.

The memory reclaim occurring in get_page_from_freelist() is also due to
heavy memory load. To get the impact of tasks in memory reclaim, this
patch adds the statistics of the memory reclaim delay statistics for
__node_reclaim().

Signed-off-by: Wen Yu Li <wenyuli@ex.bilibili.com>
---
  mm/vmscan.c | 2 ++
  1 file changed, 2 insertions(+)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 6f13394b112e..88be3dedc584 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -8026,6 +8026,7 @@ static int __node_reclaim(struct pglist_data 
*pgdat, gfp_t gfp_mask, unsigned in

  	cond_resched();
  	psi_memstall_enter(&pflags);
+	delayacct_freepages_start();
  	fs_reclaim_acquire(sc.gfp_mask);
  	/*
  	 * We need to be able to allocate from the reserves for RECLAIM_UNMAP
@@ -8048,6 +8049,7 @@ static int __node_reclaim(struct pglist_data 
*pgdat, gfp_t gfp_mask, unsigned in
  	memalloc_noreclaim_restore(noreclaim_flag);
  	fs_reclaim_release(sc.gfp_mask);
  	psi_memstall_leave(&pflags);
+	delayacct_freepages_end();

  	trace_mm_vmscan_node_reclaim_end(sc.nr_reclaimed);

-- 
2.30.2

Re: [PATCH] delayacct: add memory reclaim delay in get_page_from_freelist

[Andrew Morton]

On Wed, 20 Sep 2023 17:38:49 +0800 liwenyu <wenyuli@ex.bilibili.com> wrote:

> The current memory reclaim delay statistics only count the direct memory
> reclaim of the task in do_try_to_free_pages(). In systems with NUMA
> open, some tasks occasionally experience slower response times, but the
> total count of reclaim does not increase, using ftrace can show that
> node_reclaim has occurred.
> 
> The memory reclaim occurring in get_page_from_freelist() is also due to
> heavy memory load. To get the impact of tasks in memory reclaim, this
> patch adds the statistics of the memory reclaim delay statistics for
> __node_reclaim().

Please review Documentation/accounting/delay-accounting.rst, see if
there is some change we can make to reflect this patch.

Your email client is wordwrapping the patches - please check that for
next time.

Re: [PATCH] delayacct: add memory reclaim delay in get_page_from_freelist

[liwenyu]

> On Wed, 20 Sep 2023 17:38:49 +0800 liwenyu <wenyuli@ex.bilibili.com> wrote:
> 
>> The current memory reclaim delay statistics only count the direct memory
>> reclaim of the task in do_try_to_free_pages(). In systems with NUMA
>> open, some tasks occasionally experience slower response times, but the
>> total count of reclaim does not increase, using ftrace can show that
>> node_reclaim has occurred.
>>
>> The memory reclaim occurring in get_page_from_freelist() is also due to
>> heavy memory load. To get the impact of tasks in memory reclaim, this
>> patch adds the statistics of the memory reclaim delay statistics for
>> __node_reclaim().
> 
> Please review Documentation/accounting/delay-accounting.rst, see if
> there is some change we can make to reflect this patch.
> 
> Your email client is wordwrapping the patches - please check that for
> next time.
> 

There is no need to change the 
Documentation/accounting/delay-accounting.rst, because this patch is 
only an expansion of  memory reclaim delayacct.

Thanks!