Re: Why we are going to have to go DirectIO

From: Tatsuo Ishii <ishii(at)postgresql(dot)org>
To: kondo(dot)mitsumasa(at)lab(dot)ntt(dot)co(dot)jp
Cc: ishii(at)postgresql(dot)org, tgl(at)sss(dot)pgh(dot)pa(dot)us, magnus(at)hagander(dot)net, josh(at)agliodbs(dot)com, stefan(at)kaltenbrunner(dot)cc, jd(at)commandprompt(dot)com, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Why we are going to have to go DirectIO
Date: 2013-12-04 07:28:19
Message-ID: 20131204.162819.1459835641271977076.t-ishii@sraoss.co.jp
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>> Can we avoid the Linux kernel problem by simply increasing our shared
>> buffer size, say up to 80% of memory?
> It will be swap more easier.

Is that the case? If the system has not enough memory, the kernel
buffer will be used for other purpose, and the kernel cache will not
work very well anyway. In my understanding, the problem is, even if
there's enough memory, the kernel's cache does not work as expected.
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp

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