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From: Wu Fengguang <fengguang.wu@intel.com>
To: Michael Rubin <mrubin@google.com>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-mm@kvack.org, jack@suse.cz, riel@redhat.com,
	akpm@linux-foundation.org, david@fromorbit.com, npiggin@suse.de,
	hch@lst.de, axboe@kernel.dk
Subject: Re: [PATCH 2/3] writeback: Adding pages_dirtied and pages_entered_writeback
Date: Fri, 20 Aug 2010 10:51:11 +0800	[thread overview]
Message-ID: <20100820025111.GB5502@localhost> (raw)
In-Reply-To: <1282251447-16937-3-git-send-email-mrubin@google.com>

On Thu, Aug 19, 2010 at 01:57:26PM -0700, Michael Rubin wrote:
> To help developers and applications gain visibility into writeback
> behaviour adding four read only sysctl files into /proc/sys/vm.
> These files allow user apps to understand writeback behaviour over time
> and learn how it is impacting their performance.
> 
>    # cat /proc/sys/vm/pages_dirtied
>    3747
>    # cat /proc/sys/vm/pages_entered_writeback
>    3618

As Rik said, /proc/sys is not a suitable place.

Frankly speaking I've worked on writeback for years and never felt
the need to add these counters. What I often do is:

$ vmmon -d 1 nr_writeback nr_dirty nr_unstable

     nr_writeback         nr_dirty      nr_unstable
            68738                0            39568
            66051                0            42255
            63406                0            44900
            60643                0            47663
            57954                0            50352
            55264                0            53042
            52592                0            55715
            49922                0            58385
That is what I get when copying /dev/zero to NFS.

You can find vmmon.c in Andrew Morton's ext3-tools package.
Also attached for your convenience.

I'm very interested in Google's use case for this patch, and why
the simple /proc/vmstat based vmmon tool is not enough.

Thanks,
Fengguang

WARNING: multiple messages have this Message-ID (diff)
From: Wu Fengguang <fengguang.wu@intel.com>
To: Michael Rubin <mrubin@google.com>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-mm@kvack.org, jack@suse.cz, riel@redhat.com,
	akpm@linux-foundation.org, david@fromorbit.com, npiggin@suse.de,
	hch@lst.de, axboe@kernel.dk
Subject: Re: [PATCH 2/3] writeback: Adding pages_dirtied and pages_entered_writeback
Date: Fri, 20 Aug 2010 10:51:11 +0800	[thread overview]
Message-ID: <20100820025111.GB5502@localhost> (raw)
In-Reply-To: <1282251447-16937-3-git-send-email-mrubin@google.com>

On Thu, Aug 19, 2010 at 01:57:26PM -0700, Michael Rubin wrote:
> To help developers and applications gain visibility into writeback
> behaviour adding four read only sysctl files into /proc/sys/vm.
> These files allow user apps to understand writeback behaviour over time
> and learn how it is impacting their performance.
> 
>    # cat /proc/sys/vm/pages_dirtied
>    3747
>    # cat /proc/sys/vm/pages_entered_writeback
>    3618

As Rik said, /proc/sys is not a suitable place.

Frankly speaking I've worked on writeback for years and never felt
the need to add these counters. What I often do is:

$ vmmon -d 1 nr_writeback nr_dirty nr_unstable

     nr_writeback         nr_dirty      nr_unstable
            68738                0            39568
            66051                0            42255
            63406                0            44900
            60643                0            47663
            57954                0            50352
            55264                0            53042
            52592                0            55715
            49922                0            58385
That is what I get when copying /dev/zero to NFS.

You can find vmmon.c in Andrew Morton's ext3-tools package.
Also attached for your convenience.

I'm very interested in Google's use case for this patch, and why
the simple /proc/vmstat based vmmon tool is not enough.

Thanks,
Fengguang

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  reply	other threads:[~2010-08-20  2:51 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-08-19 20:57 [PATCH 0/3] writeback: kernel visibility Michael Rubin
2010-08-19 20:57 ` Michael Rubin
2010-08-19 20:57 ` [PATCH 1/3] mm: helper functions for dirty and writeback accounting Michael Rubin
2010-08-19 20:57   ` Michael Rubin
2010-08-20  2:34   ` Wu Fengguang
2010-08-20  2:34     ` Wu Fengguang
2010-08-20  8:19     ` Michael Rubin
2010-08-20  8:19       ` Michael Rubin
2010-08-19 20:57 ` [PATCH 2/3] writeback: Adding pages_dirtied and pages_entered_writeback Michael Rubin
2010-08-19 20:57   ` Michael Rubin
2010-08-20  2:51   ` Wu Fengguang [this message]
2010-08-20  2:51     ` Wu Fengguang
2010-08-20  6:54     ` Wu Fengguang
2010-08-20  6:54       ` Wu Fengguang
2010-08-20  8:16     ` Michael Rubin
2010-08-20  8:16       ` Michael Rubin
2010-08-20  8:43       ` Wu Fengguang
2010-08-20  8:43         ` Wu Fengguang
2010-08-20  8:43         ` Wu Fengguang
2010-08-19 20:57 ` [PATCH 3/3] writeback: Reporting dirty thresholds in /proc/vmstat Michael Rubin
2010-08-19 20:57   ` Michael Rubin
2010-08-20  3:16   ` Wu Fengguang
2010-08-20  3:16     ` Wu Fengguang
2010-08-20  8:18     ` Michael Rubin
2010-08-20  8:18       ` Michael Rubin
2010-08-19 22:11 ` [PATCH 0/3] writeback: kernel visibility Rik van Riel
2010-08-19 22:11   ` Rik van Riel

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