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

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Date:   Thu, 18 Mar 2021 20:56:20 +0800
From:   Xunlei Pang <xlpang@...ux.alibaba.com>
To:     Vlastimil Babka <vbabka@...e.cz>,
        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 3/18/21 8:18 PM, Vlastimil Babka wrote:
> 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?
> 

ss may access /proc/slabinfo to acquire network related slab statistics.