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

From: Jan Kara
Date: Thu Dec 06 2012 - 09:20:36 EST

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...


Jan Kara <jack@xxxxxxx>
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