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From: William Lee Irwin III <wli@holomorphy.com>
To: Takao Indoh <indou.takao@soft.fujitsu.com>
Cc: Mike Fedyk <mfedyk@matchmail.com>, linux-kernel@vger.kernel.org
Subject: Re: cache limit
Date: Tue, 2 Sep 2003 04:30:38 -0700	[thread overview]
Message-ID: <20030902113038.GK4306@holomorphy.com> (raw)
In-Reply-To: <23C371405B0858indou.takao@soft.fujitsu.com>

On Tue, Sep 02, 2003 at 07:52:51PM +0900, Takao Indoh wrote:
> According to this information, many I/O increase pagecache and cause
> memory shortage.
> fadvise may be effective, but fadvise always releases cache
> even if there are enough free memory, and may degrade performance.
> In the case of /proc tunable,
> pagecache is not released until system memory become lack.
[...]
> If so, limiting pagecache seems to be effective for DBMS.

There are reasons why databases use raw io and direct io; this is one
of them. I'd say the kernel shouldn't try to engage in such tunable
shenanigans.


-- wli
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On Tue, Sep 02, 2003 at 07:52:51PM +0900, Takao Indoh wrote:
> According to this information, many I/O increase pagecache and cause
> memory shortage.
> fadvise may be effective, but fadvise always releases cache
> even if there are enough free memory, and may degrade performance.
> In the case of /proc tunable,
> pagecache is not released until system memory become lack.
[...]
> If so, limiting pagecache seems to be effective for DBMS.

There are reasons why databases use raw io and direct io; this is one
of them. I'd say the kernel shouldn't try to engage in such tunable
shenanigans.


-- wli

  reply	other threads:[~2003-09-02 11:29 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-08-19  4:39 cache limit Anthony R.
2003-08-19  4:57 ` Nuno Silva
2003-08-19  5:33 ` Denis Vlasenko
2003-08-19  6:20   ` Andrew Morton
2003-08-19  9:05     ` J.A. Magallon
2003-08-19  9:16       ` Andrew Morton
2003-08-19  9:28         ` J.A. Magallon
2003-08-19  9:43           ` Andrew Morton
2003-08-19 13:32     ` Erik Andersen
2003-08-19 20:56       ` Andrew Morton
2003-08-19 14:28   ` Anthony R.
2003-08-19 18:26     ` Mike Fedyk
2003-08-19  5:42 ` Nick Piggin
2003-08-21  0:49 ` Takao Indoh
2003-08-21 23:47   ` Mike Fedyk
2003-08-25  2:45     ` Takao Indoh
2003-08-25  4:11       ` William Lee Irwin III
2003-08-25 22:58         ` Mike Fedyk
2003-08-26  9:46           ` William Lee Irwin III
2003-08-27  9:36             ` Takao Indoh
2003-08-27  9:45               ` William Lee Irwin III
2003-08-27 11:14                 ` Takao Indoh
2003-08-27 11:36                   ` William Lee Irwin III
2003-09-02 10:52                     ` Takao Indoh
2003-09-02 11:30                       ` William Lee Irwin III [this message]
2003-09-02 17:21                       ` Mike Fedyk
2003-08-27 16:01                 ` Joseph Malicki
     [not found] <m6Bv.3ys.1@gated-at.bofh.it>
     [not found] ` <mLY8.dO.5@gated-at.bofh.it>
2003-08-21  9:52   ` Ihar 'Philips' Filipau
2003-08-25  7:17     ` Takao Indoh
     [not found] <n7lV.2HA.19@gated-at.bofh.it>
     [not found] ` <ofAJ.4dx.9@gated-at.bofh.it>
     [not found]   ` <ogZM.5KJ.1@gated-at.bofh.it>
     [not found]     ` <oyDw.5FP.33@gated-at.bofh.it>
2003-08-26 10:15       ` Ihar 'Philips' Filipau
2003-08-26 17:46         ` Mike Fedyk
     [not found] <oJ5P.699.21@gated-at.bofh.it>
     [not found] ` <oJ5P.699.23@gated-at.bofh.it>
     [not found]   ` <oJ5P.699.25@gated-at.bofh.it>
     [not found]     ` <oJ5P.699.27@gated-at.bofh.it>
     [not found]       ` <oJ5P.699.19@gated-at.bofh.it>
     [not found]         ` <oQh2.4bQ.13@gated-at.bofh.it>
2003-08-26 19:08           ` Ihar 'Philips' Filipau
2003-08-26 19:23             ` Mike Fedyk
2003-08-27 10:21               ` Ihar 'Philips' Filipau
2003-08-27 11:07                 ` Nick Piggin
     [not found] <000801c36cb1$454d4950$1001a8c0@etofmv650>
2003-08-27 16:02 ` YoshiyaETO
  -- strict thread matches above, loose matches on Subject: below --
2003-08-27 16:03 Joseph Malicki

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