linux-kernel - Re: [PATCH v4 1/3] mm/slub: Introduce two counters for partial objects

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Message-ID: <42b5dba7-f89f-ae43-3b93-f6e4868e1573@suse.cz>
Date:   Thu, 18 Mar 2021 13:18:14 +0100
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Xunlei Pang <xlpang@...ux.alibaba.com>,
        Christoph Lameter <cl@...ux.com>,
        Christoph Lameter <cl@...two.de>,
        Pekka Enberg <penberg@...nel.org>,
        Roman Gushchin <guro@...com>,
        Konstantin Khlebnikov <khlebnikov@...dex-team.ru>,
        David Rientjes <rientjes@...gle.com>,
        Matthew Wilcox <willy@...radead.org>,
        Shu Ming <sming56@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Wen Yang <wenyang@...ux.alibaba.com>,
        James Wang <jnwang@...ux.alibaba.com>
Subject: Re: [PATCH v4 1/3] mm/slub: Introduce two counters for partial
 objects

On 3/17/21 8:54 AM, Xunlei Pang wrote:
> The node list_lock in count_partial() spends long time iterating
> in case of large amount of partial page lists, which can cause
> thunder herd effect to the list_lock contention.
> 
> We have HSF RT(High-speed Service Framework Response-Time) monitors,
> the RT figures fluctuated randomly, then we deployed a tool detecting
> "irq off" and "preempt off" to dump the culprit's calltrace, capturing
> the list_lock cost nearly 100ms with irq off issued by "ss", this also
> caused network timeouts.

I forgot to ask, how does "ss" come into this? It displays network connections
AFAIK. Does it read any SLUB counters or slabinfo?