Re: backing up ext4 fs, system unresponsive, thrashing like crazyeven though swap is unused

[Dimitrios Apostolou]

On Thu, 6 Dec 2012, Jan Kara wrote:
> On Sun 25-11-12 21:30:00, Dimitrios Apostolou wrote:
> > On Sun, 2012-11-25 at 15:55 +0200, Dimitrios Apostolou wrote:
> > > on an old PIII-500MHz laptop, 128MB RAM, kernel 3.6.6, I started a
> > > backup process (tar|xz -4, nice'd and ionice'd -c3) from ext4 on local
> > > ATA disk to ext3 on external USB disk (USB-2.0 port on PCMCIA card).
> > > Even though earlier system load was minimal, free memory was plenty, the
> > > system now is unresponsive and is thrashing the disk, but the swapfile
> > > is rarely touched.
> >
> > I'm now having the same experience even though I replaced xz (which
> > needed ~50MB RAM) with gzip. Even though I feel the realtime root shell
> > is a bit more responsive than before, the OOM killer is out killing
> > small processes like syslog-ng and systemd-logind... The
> > ext4_inode_cache slab is taking almost all my memory (117MB). Please
> > advise!
>  Hmm, it seems commit 4eff96dd5283a102e0c1cac95247090be74a38ed might be
> interesting for you. It landed in -stable kernels recently as well if I
> remember right...

Thanks, I appreciate your help as I'm stuck in a dead end now, and I've 
been trying to write some debug hook that prints all ext4_inodes and the 
reason they are pinned (is there an easy way to find this out?).

So maybe there is a typo in the SHA1 sum you provided? Gitweb can't find 
it in Linus' tree.


Thanks,
Dimitris

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