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Re: filesystem slowdown with backports kernel


On Wed, Oct 17, 2018 at 01:41:56PM +0200, Jens Holzkämper wrote:
> Hi,
> we have a NAS system acting as a place to store our server's backups
> (via rsync with link-dest). On that NAS we switched from the stable
> kernel (4.9) to the one provided by backports (4.18) because of an
> unrelated problem. When we do that, we see a slowdown of our backup
> process, from the backup via rsync itself to deleting old backup
> directories. The slowdown seems to be connected to the number of
> files/directories as backups of systems with less files seem less
> affected than the ones with many files.

I'd complete your tests with an invocation of 'perf record/perf top' on
NFS server side.
The reason being - you'll be able to point out at particular
kernel/userspace functions that are responsible for this slowdown.