swap_pager: indefinite wait buffer

[Kris Kennaway]

Michael Grant wrote:
> On Wed, Mar 5, 2008 at 11:08 AM, Ruben van Staveren <ruben at verweg.com> wrote:
>>  On 5 Mar 2008, at 10:06, Michael Grant wrote:
>>
>>  > My server just literally was brought to it's knees with this message
>>  > spewing on the console:
>>  >
>>  > swap_pager: indefinite wait buffer: bufobj: 0, blkno: 1203133, size:
>>  > 4096
>>  >
>>  > (blkno and size were varying)
>>  >
>>  > Some searching says that this is or was a bug.  Has this been fixed
>>  > yet?  If so, what should I upgrade to?  I'm currently running 6.3
>>
>>  You may consider partition backed swap instead of file backed swap if
>>  that is the case.
> 
> Hmm, I can't easily do that, I didn't leave any empty partitions
> around as I never considered swapping to a file to be a so bad.
> 
> Is swapping to a file so bad under normal conditions?

The message indicates that it took >30 seconds to complete an operation, 
so it was timed out assuming the I/O was lost by the device.

In your case it was probably not lost, just delayed for more than 30 
seconds by an overloaded filesystem.

> Does this mean that this bug is still not fixed in 7.0?

It's not clear whether it's a bug or your disk is just too overloaded to 
complete the filesystem operation in a reasonable time period (swapping 
to a file is slower than swapping to a partition, which is already 
something you never want to do in normal operation).  You can increase 
the timeout by editing the kernel.

Kris