From: "Alexander V. Lukyanov" <lav@netis.ru>
Subject: Re: PATCH: allow inode_readahead_blks=0
Date: Wed, 17 Nov 2010 10:48:54 +0300
Message-ID: <20101117074850.GA29191@proxy>
References: <20101116080546.GA7949@proxy>
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On Tue, Nov 16, 2010 at 11:05:46AM +0300, Alexander V. Lukyanov wrote:
> Currently the value 0 is disallowed, as it is not a power of 2.

BTW, the default value inode_readahead_blks=32 gives me troubles: it raises
load average and increases request latency on a busy squid server. I
explain it by random access to large number of files which are present in
the squid cache.

BTW2: the value of 0 should be allowed, it is explicitly used by the code:
                /*
                 * If we need to do any I/O, try to pre-readahead extra
                 * blocks from the inode table.
                 */
                if (EXT4_SB(sb)->s_inode_readahead_blks) {
			...
		}
-- 
   Alexander.