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Date: Wed, 07 Nov 2018 11:49:44 +0530
From: Arun KS <arunks@codeaurora.org>
Subject: Re: [PATCH v1 0/4]mm: convert totalram_pages, totalhigh_pages and
 managed pages to atomic
In-Reply-To: <20181106162206.0f43c1eb16c3dd812bdadbdd@linux-foundation.org>
References: <1540551662-26458-1-git-send-email-arunks@codeaurora.org>
 <20181106162206.0f43c1eb16c3dd812bdadbdd@linux-foundation.org>
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To: Andrew Morton <akpm@linux-foundation.org>
Cc: keescook@chromium.org, khlebnikov@yandex-team.ru, minchan@kernel.org, getarunks@gmail.com, gregkh@linuxfoundation.org, mhocko@kernel.org, vbabka@suse.cz, linux-kernel@vger.kernel.org, linux-mm@kvack.org

On 2018-11-07 05:52, Andrew Morton wrote:
> On Fri, 26 Oct 2018 16:30:58 +0530 Arun KS <arunks@codeaurora.org> 
> wrote:
> 
>> This series convert totalram_pages, totalhigh_pages and
>> zone->managed_pages to atomic variables.
> 
> The whole point appears to be removal of managed_page_count_lock, yes?
> 
> Why?  What is the value of this patchset?  If "performance" then are 
> any
> measurements available?

Hello Andrew,

https://patchwork.kernel.org/patch/10670787/
In version 2, I have added motivation behind this conversion. Pasting 
same here,

totalram_pages, zone->managed_pages and totalhigh_pages updates are 
protected by managed_page_count_lock, but readers never care about it. 
Convert these variables to atomic to avoid readers potentially seeing a 
store tear. I don't think we have a performance improvement here.

Regards,
Arun