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From: "NeilBrown" <neilb@suse.de>
To: "Mel Gorman" <mgorman@techsingularity.net>
Cc: "Andrew Morton" <akpm@linux-foundation.org>,
	"Theodore Ts'o" <tytso@mit.edu>,
	"Andreas Dilger" <adilger.kernel@dilger.ca>,
	"Darrick J . Wong" <djwong@kernel.org>,
	"Matthew Wilcox" <willy@infradead.org>,
	"Michal Hocko" <mhocko@suse.com>,
	"Dave Chinner" <david@fromorbit.com>,
	"Rik van Riel" <riel@surriel.com>,
	"Vlastimil Babka" <vbabka@suse.cz>,
	"Johannes Weiner" <hannes@cmpxchg.org>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Linux-MM" <linux-mm@kvack.org>,
	"Linux-fsdevel" <linux-fsdevel@vger.kernel.org>,
	"LKML" <linux-kernel@vger.kernel.org>,
	"Mel Gorman" <mgorman@techsingularity.net>
Subject: Re: [PATCH 7/8] mm/vmscan: Increase the timeout if page reclaim is not making progress
Date: Fri, 22 Oct 2021 12:07:43 +1100	[thread overview]
Message-ID: <163486486314.17149.7181265861483962024@noble.neil.brown.name> (raw)
In-Reply-To: <20211019090108.25501-8-mgorman@techsingularity.net>

On Tue, 19 Oct 2021, Mel Gorman wrote:
> Tracing of the stutterp workload showed the following delays
> 
>       1 usect_delayed=124000 reason=VMSCAN_THROTTLE_NOPROGRESS
>       1 usect_delayed=128000 reason=VMSCAN_THROTTLE_NOPROGRESS
>       1 usect_delayed=176000 reason=VMSCAN_THROTTLE_NOPROGRESS
>       1 usect_delayed=536000 reason=VMSCAN_THROTTLE_NOPROGRESS
>       1 usect_delayed=544000 reason=VMSCAN_THROTTLE_NOPROGRESS
>       1 usect_delayed=556000 reason=VMSCAN_THROTTLE_NOPROGRESS
>       1 usect_delayed=624000 reason=VMSCAN_THROTTLE_NOPROGRESS
>       1 usect_delayed=716000 reason=VMSCAN_THROTTLE_NOPROGRESS
>       1 usect_delayed=772000 reason=VMSCAN_THROTTLE_NOPROGRESS
>       2 usect_delayed=512000 reason=VMSCAN_THROTTLE_NOPROGRESS
>      16 usect_delayed=120000 reason=VMSCAN_THROTTLE_NOPROGRESS
>      53 usect_delayed=116000 reason=VMSCAN_THROTTLE_NOPROGRESS
>     116 usect_delayed=112000 reason=VMSCAN_THROTTLE_NOPROGRESS
>    5907 usect_delayed=108000 reason=VMSCAN_THROTTLE_NOPROGRESS
>   71741 usect_delayed=104000 reason=VMSCAN_THROTTLE_NOPROGRESS
> 
> All the throttling hit the full timeout and then there was wakeup delays
> meaning that the wakeups are premature as no other reclaimer such as
> kswapd has made progress. This patch increases the maximum timeout.

Would love to see the comparable tracing results for after the patch.

Thanks,
NeilBrown


> 
> Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
> Acked-by: Vlastimil Babka <vbabka@suse.cz>
> ---
>  mm/vmscan.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 1f5c467dc83c..ec2006680242 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1033,6 +1033,8 @@ void reclaim_throttle(pg_data_t *pgdat, enum vmscan_throttle_state reason)
>  	 */
>  	switch(reason) {
>  	case VMSCAN_THROTTLE_NOPROGRESS:
> +		timeout = HZ/2;
> +		break;
>  	case VMSCAN_THROTTLE_WRITEBACK:
>  		timeout = HZ/10;
>  
> -- 
> 2.31.1
> 
> 

  reply	other threads:[~2021-10-22  1:07 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-19  9:01 [PATCH v4 0/8] Remove dependency on congestion_wait in mm/ Mel Gorman
2021-10-19  9:01 ` [PATCH 1/8] mm/vmscan: Throttle reclaim until some writeback completes if congested Mel Gorman
2021-10-19  9:01 ` [PATCH 2/8] mm/vmscan: Throttle reclaim and compaction when too may pages are isolated Mel Gorman
2021-10-19 17:12   ` Yang Shi
2021-10-19  9:01 ` [PATCH 3/8] mm/vmscan: Throttle reclaim when no progress is being made Mel Gorman
2021-10-19  9:01 ` [PATCH 4/8] mm/writeback: Throttle based on page writeback instead of congestion Mel Gorman
2021-10-19  9:01 ` [PATCH 5/8] mm/page_alloc: Remove the throttling logic from the page allocator Mel Gorman
2021-10-19  9:20   ` Vlastimil Babka
2021-10-19  9:01 ` [PATCH 6/8] mm/vmscan: Centralise timeout values for reclaim_throttle Mel Gorman
2021-10-22  1:06   ` NeilBrown
2021-10-22  8:12     ` Mel Gorman
2021-10-19  9:01 ` [PATCH 7/8] mm/vmscan: Increase the timeout if page reclaim is not making progress Mel Gorman
2021-10-22  1:07   ` NeilBrown [this message]
2021-10-22  8:14     ` Mel Gorman
2021-10-19  9:01 ` [PATCH 8/8] mm/vmscan: Delay waking of tasks throttled on NOPROGRESS Mel Gorman
2021-10-19 22:00 ` [PATCH v4 0/8] Remove dependency on congestion_wait in mm/ Andrew Morton
2021-10-20  8:44   ` Mel Gorman
2021-10-22  1:15 ` NeilBrown
2021-10-22  8:39   ` Mel Gorman
2021-10-22 11:26     ` NeilBrown
2021-10-22 13:17       ` Mel Gorman
2021-10-27  0:43         ` NeilBrown
2021-10-27 10:13           ` Mel Gorman
  -- strict thread matches above, loose matches on Subject: below --
2021-10-22 14:46 [PATCH v5 " Mel Gorman
2021-10-22 14:46 ` [PATCH 7/8] mm/vmscan: Increase the timeout if page reclaim is not making progress Mel Gorman
2021-10-08 13:53 [PATCH v3 0/8] Remove dependency on congestion_wait in mm/ Mel Gorman
2021-10-08 13:53 ` [PATCH 7/8] mm/vmscan: Increase the timeout if page reclaim is not making progress Mel Gorman
2021-10-14 15:39   ` Vlastimil Babka

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