On Wed, Nov 30, 2011 at 09:04:11PM +0800, Christian Ehrhardt wrote:

On 11/28/2011 03:39 AM, Wu Fengguang wrote:

quoted

On Fri, Nov 25, 2011 at 08:36:33AM +0800, Dave Chinner wrote:

quoted

On Thu, Nov 24, 2011 at 11:28:22PM +0100, Jan Kara wrote:

quoted

On Mon 21-11-11 19:35:40, Wu Fengguang wrote:

quoted

On Mon, Nov 21, 2011 at 06:01:37PM +0800, Christoph Hellwig wrote:

quoted

On Mon, Nov 21, 2011 at 05:18:21PM +0800, Wu Fengguang wrote:

quoted

From: Nikanth Karthikesan<redacted>

[...]

quoted

quoted

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"

-- 

GrA 1/4 sse / regards, Christian Ehrhardt
IBM Linux Technology Center, System z Linux Performance

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