From: Minchan Kim <minchan@kernel.org>
To: Vinayak Menon <vinmenon@codeaurora.org>
Cc: akpm@linux-foundation.org, hannes@cmpxchg.org,
mgorman@techsingularity.net, vbabka@suse.cz, mhocko@suse.com,
riel@redhat.com, vdavydov.dev@gmail.com,
anton.vorontsov@linaro.org, shiraz.hashim@gmail.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: vmscan: do not pass reclaimed slab to vmpressure
Date: Thu, 26 Jan 2017 08:27:13 +0900 [thread overview]
Message-ID: <20170125232713.GB20811@bbox> (raw)
In-Reply-To: <1485344318-6418-1-git-send-email-vinmenon@codeaurora.org>
Hello Vinayak,
On Wed, Jan 25, 2017 at 05:08:38PM +0530, Vinayak Menon wrote:
> It is noticed that during a global reclaim the memory
> reclaimed via shrinking the slabs can sometimes result
> in reclaimed pages being greater than the scanned pages
> in shrink_node. When this is passed to vmpressure, the
I don't know you are saying zsmalloc. Anyway, it's one of those which
free larger pages than requested. I should fix that but was not sent
yet, unfortunately.
> unsigned arithmetic results in the pressure value to be
> huge, thus resulting in a critical event being sent to
> root cgroup. Fix this by not passing the reclaimed slab
> count to vmpressure, with the assumption that vmpressure
> should show the actual pressure on LRU which is now
> diluted by adding reclaimed slab without a corresponding
> scanned value.
I can't guess justfication of your assumption from the description.
Why do we consider only LRU pages for vmpressure? Could you elaborate
a bit?
Thanks.
>
> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
> ---
> mm/vmscan.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 947ab6f..37c4486 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2594,16 +2594,16 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
> sc->nr_scanned - nr_scanned,
> node_lru_pages);
>
> - if (reclaim_state) {
> - sc->nr_reclaimed += reclaim_state->reclaimed_slab;
> - reclaim_state->reclaimed_slab = 0;
> - }
> -
> /* Record the subtree's reclaim efficiency */
> vmpressure(sc->gfp_mask, sc->target_mem_cgroup, true,
> sc->nr_scanned - nr_scanned,
> sc->nr_reclaimed - nr_reclaimed);
>
> + if (reclaim_state) {
> + sc->nr_reclaimed += reclaim_state->reclaimed_slab;
> + reclaim_state->reclaimed_slab = 0;
> + }
> +
> if (sc->nr_reclaimed - nr_reclaimed)
> reclaimable = true;
>
> --
> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a
> member of the Code Aurora Forum, hosted by The Linux Foundation
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
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next prev parent reply other threads:[~2017-01-25 23:27 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-25 11:38 [PATCH] mm: vmscan: do not pass reclaimed slab to vmpressure Vinayak Menon
2017-01-25 23:27 ` Minchan Kim [this message]
2017-01-26 5:23 ` vinayak menon
2017-01-26 14:18 ` Minchan Kim
2017-01-27 8:13 ` vinayak menon
2017-01-30 23:40 ` Minchan Kim
2017-06-06 13:00 ` zhong jiang
2017-06-07 2:53 ` Minchan Kim
2017-06-07 3:07 ` zhong jiang
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