[dm-crypt] md + dm-crypt + lvm2: I/O slows down system, I/O schedule ineffective

Marc Ballarin Ballarin.Marc at gmx.de
Thu Feb 23 11:57:27 CET 2012


Hi,

Am 23.02.2012 11:19, schrieb Günter Merz:
> I'm experiencing unresponsiveness and a general system slowdown when I'm unpacking big archives or building a big packages (during builds I'm only using max 2 cores). To counter this, I've been experimenting with nice and ionice. Unfortunately, ionice -c3 before big I/O traffic doesn't seem to make any difference. The responsiveness is still really bad at times.
This sounds like those (more or less) well-known hugepage issues.

You could try "echo madvise > 
/sys/kernel/mm/transparent_hugepage/defrag" (or "echo never...") if your 
kernel is configured to use transparent hugepages (which most modern 
distribution kernels are).

If this is your issue, the bug isn't really caused by dm-crypt, but by 
Linux memory management issues and it is completely unrelated to ionice 
or io scheduler settings.

Regards,
Marc



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