linux-kernel - Re: [PATCH] mm/page_alloc: simplify kmem cgroup charge/uncharge code

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20201208071451.GA87765@rlk>
Date:   Tue, 8 Dec 2020 15:14:51 +0800
From:   Hui Su <sh_def@....com>
To:     linux-kernel@...r.kernel.org, sh_def@....com
Subject: Re: [PATCH] mm/page_alloc: simplify kmem cgroup charge/uncharge code

On Mon, Dec 07, 2020 at 09:28:46AM -0800, Shakeel Butt wrote:
> On Mon, Dec 7, 2020 at 6:22 AM Hui Su <sh_def@....com> wrote:
> 
> The reason to keep __memcg_kmem_[un]charge_page functions is that they
> were called in the very hot path. Can you please check the performance
> impact of your change and if the generated code is actually same or
> different.

Hi, Shakeel:

I objdump the mm/page_alloc.o and comapre them, it change the assemble code
indeed. In fact, it change some code order, which i personally think won't have
impact on performance. And i ran the ltp mm and conatiner test, it seems nothing
abnormal.

BUT i still want to check whether this change will have negative impact on
perforance due to this change code was called in the very hot path like you
said, AND saddly i did not find a way to quantify the impact on performance.
Can you give me some suggestion about how to quantify the performance or some
tool?

Thanks.