Messages in this thread | | | Date | Wed, 30 Nov 2011 14:04:11 +0100 | From | Christian Ehrhardt <> | Subject | Re: [PATCH 2/8] readahead: make default readahead size a kernel parameter |
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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@suse.de> >>>>>> [...]
>> >> 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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