On Wed, Nov 30, 2011 at 09:04:11PM +0800, Christian Ehrhardt wrote:
>
>
> 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.
It's a really good example, thank you!
> 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"
So SLES (@s390 and maybe more) is already shipping with 512kb
readahead size? Good to know this!
Thanks,
Fengguang
>
>
>
> LABEL="ra_end"
>
> --
>
> Grüsse / regards, Christian Ehrhardt
> IBM Linux Technology Center, System z Linux Performance
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