linux-kernel - Re: [PATCH v3 3/7] mm/lru: replace pgdat lru

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Message-ID: <1199177d-6f34-3aae-3eb6-8fac42f070a1@linux.alibaba.com>
Date:   Tue, 19 Nov 2019 18:10:09 +0800
From:   Alex Shi <alex.shi@...ux.alibaba.com>
To:     Daniel Jordan <daniel.m.jordan@...cle.com>
Cc:     cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, akpm@...ux-foundation.org,
        mgorman@...hsingularity.net, tj@...nel.org, hughd@...gle.com,
        khlebnikov@...dex-team.ru, yang.shi@...ux.alibaba.com,
        willy@...radead.org, Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Roman Gushchin <guro@...com>,
        Shakeel Butt <shakeelb@...gle.com>,
        Chris Down <chris@...isdown.name>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vlastimil Babka <vbabka@...e.cz>, Qian Cai <cai@....pw>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
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        Yafang Shao <laoar.shao@...il.com>
Subject: Re: [PATCH v3 3/7] mm/lru: replace pgdat lru_lock with lruvec lock



在 2019/11/19 上午10:10, Daniel Jordan 写道:
>> -	if (pgdat)
>> -		spin_unlock_irqrestore(&pgdat->lru_lock, flags);
>> +
>>  	release_pages(pvec->pages, pvec->nr);
>>  	pagevec_reinit(pvec);
>>  }
> Why can't you keep the locking pattern where we only drop and reacquire if the
> lruvec changes?  It'd save a lot of locks and unlocks if most pages were from
> the same memcg and node, or the memory controller were unused.
> 

Good catching! This issue will be fixed in the next patch which introduce relock_ function.

Thanks!