linux-ext4 - Re: [RFC, PATCH] Avoid hot statistics cache line in ext4 extent cache

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Message-ID: <CAMQXfUcH-0Krg811msFVbC25qY1mPTdrMi8Rg-qJST=6B-s_5w@mail.gmail.com>
Date:	Mon, 26 Mar 2012 15:26:28 -0700
From:	Vivek Haldar <haldar@...gle.com>
To:	Andi Kleen <ak@...ux.intel.com>
Cc:	Andreas Dilger <adilger@...ger.ca>, tytso@....edu,
	linux-ext4@...r.kernel.org, tim.c.chen@...ux.intel.com
Subject: Re: [RFC, PATCH] Avoid hot statistics cache line in ext4 extent cache

Andi --

I realized the problem soon after the original patch, and submitted
another patch to make these per cpu  counters.

http://patchwork.ozlabs.org/patch/124213/

However, looks like that fell through the cracks.

Andreas, Ted --  could you please take a look at that patch?

Andi --  perhaps you could patch it in  and check if  you still see
the hot cache line?

On Fri, Mar 23, 2012 at 8:13 PM, Andi Kleen <ak@...ux.intel.com> wrote:
>> The patch only disables the statistics counting, but not the sysfs
>> files that will now report bogus statistics.  I don't disagree with
>> disabling these stats, but if you are disabling the accounting you
>> should also comment out the functions in fs/ext4/super.c that are
>> printing out these statistics.
>
> Aware of that -- that is why it was just a RFC.
> The choice is between per cpu counters or completely removing them.
> I would prefer the later.
>
> -Andi
>
> --
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-- 
Regards,
Vivek
--
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