Re: [exim] Exim message thaw performance

Volker Schmelich, 22.08.2012 22:15:
> Thank you for the tip regarding strace. From a first glance it looks like server 2 loses time between "Writing spool header file" and "LOG: MAIN unfrozen by root". Especially some fstat(), fsync(), close() call lines have higher times displayed when using strace with the -r param.
>
> E.g. one close() shows 0.000644 on server 1 and the same close() on server 2 shows 0.032874.

close() of file read or written to?
Maybe you could put the strace outputs (-o /tmp/strace) on some webserver...

> So my uneducated guess would be that ext4 is to blame. Is there a way to temporarily make ext4 behave like ext3 and re-run the test?

It should be possible to mount the volume as ext3 (unless a
non-backwards-compatible ext4 feature was enabled, obviously).
Or just create a new ext3 partition, copy your spool there and mount it
over /var/spool/exim.

There are some ext4 options that may change performance, e.g.
noauto_da_alloc, nobarrier, journal_data_writeback.