Date:   Wed, 12 Jan 2022 00:25:51 +0000
From:   Wei Yang <richard.weiyang@gmail.com>
To:     Roman Gushchin <guro@fb.com>
Cc:     Wei Yang <richard.weiyang@gmail.com>, hannes@cmpxchg.org,
        mhocko@kernel.org, vdavydov.dev@gmail.com,
        akpm@linux-foundation.org, shakeelb@google.com, vbabka@suse.cz,
        willy@infradead.org, songmuchun@bytedance.com, shy828301@gmail.com,
        surenb@google.com, linux-kernel@vger.kernel.org,
        cgroups@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 4/4] mm/memcg: refine
 mem_cgroup_threshold_ary->current_threshold calculation
Message-ID: <20220112002551.sksmoril2nwuddtu@master>
Reply-To: Wei Yang <richard.weiyang@gmail.com>
References: <20220111010302.8864-1-richard.weiyang@gmail.com>
 <20220111010302.8864-4-richard.weiyang@gmail.com>
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On Tue, Jan 11, 2022 at 10:23:41AM -0800, Roman Gushchin wrote:
>On Tue, Jan 11, 2022 at 01:03:02AM +0000, Wei Yang wrote:
>> mem_cgroup_threshold_ary->current_threshold points to the last entry
>> who's threshold is less or equal to usage.
>> 
>> Instead of iterating entries to get the correct index, we can leverage
>> primary->current_threshold to get it. If the threshold added is less or
>> equal to usage, current_threshold should increase by one. Otherwise, it
>> doesn't change.
>
>How big is usually an array of thresholds? If it's not huge, likely
>any savings won't be really noticeable (it's not a hot path and there
>is an rc_synchronize() below).

Usually the size is small I think.

>
>So I agree with Michal that a better justification is really needed.

Yep.

>
>Thanks!

-- 
Wei Yang
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