On 03/25/2012 01:39 PM, Hugh Dickins wrote:

On Fri, 23 Mar 2012, Jason Mattax wrote:

quoted

On 03/23/2012 06:05 AM, Hugh Dickins wrote:

quoted

I'm not surprised that you saw no problem on 2.6.32.27, but I am
very surprised that you see the problem on 2.6.33.1 - I'm wondering
if that's a typo for something else, or a distro kernel which actually
contains changes from later releases?

I can't say why I saw it then, but I got the 2.6.33.1 kernel off of
http://www.kernel.org/pub/linux/kernel/v2.6/ so that I wouldn't have to worry
about distribution changes when reporting the bug here. I just recompiled the
source and verified that it is still affected even with the newest firmware.

Thank you for going to that trouble to narrow it down, thank you for
confirming, and I apologize for shedding doubt on your finding.

It appears that there's something else involved here, which I know nothing
about as yet; perhaps an earlier change in block layer handling of discard.

Although it's just history now, I ought to investigate once my Vertex2
arrives - well, several weeks later, I won't have time immediately.

Please would you clarify one thing.  2.6.33.1 was the earliest kernel
you saw the slowdown on.  I assume from that that you tried 2.6.33 itself,
and it did not show the slowdown.  Or were you testing releases in some
other order? if so please let me know the latest without the slowdown.

Thanks,
Hugh

I attempted to test on 2.6.33, but I was unable to get it to boot with 
the exact same .config file as the one I used for 2.6.33.1, based on the 
bit of the stack trace I could see it looked like something was killing 
init. Everything else was the same between booting those kernels and 
2.6.32.27 booted just fine as did all the kernels I tested past 
2.6.33.1, since I was focused on finding where the flaw was I figured 
that within 2 revisions was good enough.

in summary
2.6.32.27 - booted and swapon worked fine
2.6.33 - failed to boot
2.6.33.1 - booted and swapon was slow

Looking back at it it appears that you weren't in the list of 
maintainers I got by running the suggested script, I'll attach email, 
and its attachments to this one.
Jason

-- 
Jason Mattax
575-418-1791
jmattax@storytotell.org