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Reply-To: xlpang@linux.alibaba.com
Subject: Re: [PATCH v4 1/3] mm/slub: Introduce two counters for partial
 objects
To:     Vlastimil Babka <vbabka@suse.cz>,
        Xunlei Pang <xlpang@linux.alibaba.com>,
        Christoph Lameter <cl@linux.com>,
        Christoph Lameter <cl@gentwo.de>,
        Pekka Enberg <penberg@kernel.org>,
        Roman Gushchin <guro@fb.com>,
        Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
        David Rientjes <rientjes@google.com>,
        Matthew Wilcox <willy@infradead.org>,
        Shu Ming <sming56@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>
Cc:     linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Wen Yang <wenyang@linux.alibaba.com>,
        James Wang <jnwang@linux.alibaba.com>
References: <1615967692-80524-1-git-send-email-xlpang@linux.alibaba.com>
 <1615967692-80524-2-git-send-email-xlpang@linux.alibaba.com>
 <42b5dba7-f89f-ae43-3b93-f6e4868e1573@suse.cz>
From:   Xunlei Pang <xlpang@linux.alibaba.com>
Message-ID: <34a07677-3afe-465c-933e-dc9503e9634d@linux.alibaba.com>
Date:   Thu, 18 Mar 2021 20:56:20 +0800
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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.