Re: Page alloc problems with 2.6.32-rc kernels

Re: Page alloc problems with 2.6.32-rc kernels

[Frans Pop]

Adding a few more CCs.

On Monday 02 November 2009, Michael Guntsche wrote:
> > I have the server running with all with patches applied and it runs
> > without any issues. Since adding patch5 seems to make a difference I
> > will revert 1-4 and only apply patch 5 to see if it work too. I will
> > report back as soon as I have news.
>
> Current status of my tests here. With only patch 5 applied (the revert)
> I am not able to reproduce the problem. Reading through the ml archives
> I noticed that this revert is somewhat controversial since it seems to
> fix other bugs. Is it possible that reverting those fixes just hide the
> bug I am seeing instead of fixing it?

Thanks Michael. That means we now have two cases where reverting the 
congestion_wait() changes from .31-rc3 (8aa7e847d8 + 373c0a7ed3) makes a 
clear and significant difference.

I wonder if more effort could/should be made on this aspect.

Cheers,
FJP

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Re: Page alloc problems with 2.6.32-rc kernels

[Michael Guntsche]

On 04 Nov 09 01:14, Frans Pop wrote:
> Thanks Michael. That means we now have two cases where reverting the 
> congestion_wait() changes from .31-rc3 (8aa7e847d8 + 373c0a7ed3) makes a 
> clear and significant difference.
> 
> I wonder if more effort could/should be made on this aspect.

Good morning Frans,

As a cross check I reverted the revert here and tried to reproduce the
problem again. It is a lot harder to trigger for me now (I was not able
to reproduce it yet). I did update my local git tree though, can you
reproduce this problem on your side with current git?

Kind regards,
Michael

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Re: Page alloc problems with 2.6.32-rc kernels

[Frans Pop]

On Wednesday 04 November 2009, Michael Guntsche wrote:
> On 04 Nov 09 01:14, Frans Pop wrote:
> > Thanks Michael. That means we now have two cases where reverting the
> > congestion_wait() changes from .31-rc3 (8aa7e847d8 + 373c0a7ed3) makes
> > a clear and significant difference.
> >
> > I wonder if more effort could/should be made on this aspect.
>
> As a cross check I reverted the revert here and tried to reproduce the
> problem again. It is a lot harder to trigger for me now (I was not able
> to reproduce it yet). I did update my local git tree though,

OK. Can you tell us a bit more about your setup:
- how much RAM does the system have?
- what's so special about mutt in your case that it triggers these errors?
  - do you maybe have a huge mailbox, so mutt uses a lot of memory?
  - does starting/use mutt cause swapping when you see the errors?
- do you use disk encryption at all?
  - if you do, what is encrypted: the file system, swap, both?

From your first mail it does look as if you had little free memory and that 
swap was in use.

> can you reproduce this problem on your side with current git?

Yes I can, but my test case is somewhat special as it forces a huge amount 
of swapping. It does look as if your problem may also be related to 
swapping activity.

Cheers,
FJP

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Re: Page alloc problems with 2.6.32-rc kernels

[Michael Guntsche]

On 04 Nov 09 23:14, Frans Pop wrote:
> OK. Can you tell us a bit more about your setup:
> - how much RAM does the system have?
512MB 
> - what's so special about mutt in your case that it triggers these errors?
>   - do you maybe have a huge mailbox, so mutt uses a lot of memory?
>   - does starting/use mutt cause swapping when you see the errors?
Mutt is accessing a maildir directory with a several subdirectories
directly. All of them are added as mailboxes so I can jump to unread
mails. During startup and folder changing mutt is accessing all the
mailboxes.
> 
> From your first mail it does look as if you had little free memory and that 
> swap was in use.
I noticed that as well.
During the last days memory usage was not that high so maybe this
is the reason why I did not see any errors. I will continue running 
latest git and see if a get the errors again when more memory is being
used.

Kind regards,
Michael

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