Re: IPR driver performance issue

[Brian King <brking@us.ibm.com>]

I think this is a libsysfs/iprutils issue due to a sysfs change in 
recent kernels. Install sysfsutils 1.3.0, then grab the latest iprutils 
package from 
http://prdownloads.sourceforge.net/iprdd/iprutils-2.0.15.4-1.src.rpm?download.
Rebuild against libsysfs 1.3 with --target=ppc and upgrade the package. 
Restart the following iprutils init.d services: iprinit, iprupdate, 
iprdump and re-run your test.

Brian

Sonny Rao wrote:
> Hi Brian, 
> 
> I recently noticed a severe regression on certain
> filesystems for a simple dd create test.  The odd thing was that
> filesystems which implemented the "writepages" aop along with
> "writepage" aop (which all writable filesystems implement) didn't seem
> to suffer nearly as much.  So, I was thinking that maybe TCQ or
> something isn't quite working correctly.
> 
> I have tried the same file creation test on non-local fibre storage
> and don't see the degredation there, and we don't see it on x86 or
> x86-64 either.
> 
> I noticed the problem in 2.6.13-rc6 but I tracked it down to a patch
> that went into 2.6.12-rc5 which looks fairly benign.  It was a merge
> from Greg-KH's device driver tree into mainline:
> 
> http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=05d3794aa8bd3b2c9f7920a05003c331cdeb75c5
> 
> I have confirmed on multiple IPR machines that if I revert this patch
> from 2.6.12-rc5, I see huge ( over 2x in some cases) improvements in
> the dd file create test on the affected filesystems.
> 
> Do you have any idea why this would happen? 
> 
> The only suspicious looking part to me is this one from
> drivers/base/core.c 
> 
> @@ -89,7 +87,6 @@ static void device_release(struct kobjec
> static struct kobj_type ktype_device = {
> .release = device_release,
> .sysfs_ops = &dev_sysfs_ops,
> - .default_attrs = dev_default_attrs,
> };
> 
> But I really have no idea what is going on
> 
> I've attached the script I was using for the tests, the filesystems
> which regress are ext3, xfs, and reiserfs.  Just edit the variables at
> the top for block device and mount-point for whatever machine you want
> to run on. 
> 
> Thanks,
> 
> Sonny Rao