Re: [PATCH 2/8] readahead: make default readahead size a kernel parameter
From: Christian Ehrhardt
Date: Wed Nov 30 2011 - 08:04:28 EST
On 11/28/2011 03:39 AM, Wu Fengguang wrote:
On Fri, Nov 25, 2011 at 08:36:33AM +0800, Dave Chinner wrote:
On Thu, Nov 24, 2011 at 11:28:22PM +0100, Jan Kara wrote:
On Mon 21-11-11 19:35:40, Wu Fengguang wrote:
On Mon, Nov 21, 2011 at 06:01:37PM +0800, Christoph Hellwig wrote:
On Mon, Nov 21, 2011 at 05:18:21PM +0800, Wu Fengguang wrote:
From: Nikanth Karthikesan<knikanth@xxxxxxx>
[...]
And one that has already been in use for exactly this purpose for
years. Indeed, it's far more flexible because you can give different
types of devices different default readahead settings quite easily,
and it you can set different defaults for just about any tunable
parameter (e.g. readahead, ctq depth, max IO sizes, etc) in the same
way.
I'm interested in this usage, too. Would you share some of your rules?
FYI - This is an example of a rules Suse delivers in SLES @ s390 for a
while now. With little modifications it could be used for all Dave
mentioned above.
cat /etc/udev/rules.d/60-readahead.rules
#
# Rules to set an increased default max readahead size for s390 disk
devices
# This file should be installed in /etc/udev/rules.d
#
SUBSYSTEM!="block", GOTO="ra_end"
ACTION!="add", GOTO="ra_end"
# on device add set initial readahead to 512 (instead of in kernel 128)
KERNEL=="sd*[!0-9]", ATTR{queue/read_ahead_kb}="512"
KERNEL=="dasd*[!0-9]", ATTR{queue/read_ahead_kb}="512"
LABEL="ra_end"
--
Grüsse / regards, Christian Ehrhardt
IBM Linux Technology Center, System z Linux Performance
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