Re: linux-2.6.23 - acting funny

From: Ingo Molnar
Date: Fri Oct 12 2007 - 02:05:41 EST



* poison <rc.poison@xxxxxxxxx> wrote:

> Also the transfer rate didn't degrade too much for copying directly
> from reiserfs to reiserfs and not using encfs:
>
> dd if=/mnt/.backup/2CpGkrxvz6wgA0b0xloz8PavzMLrMymOgi9 of=/mnt/.tdata/test
> 1033+0 records in
> 1033+0 records out
> 1083179008 bytes (1.1 GB) copied, 16.9303 s, 64.0 MB/s
>
> Plus the transfer rate doesn't increase if I start a CPU hog while
> copying between reiserfs.
>
> So it looks more to me like theres a bad interaction between the new
> scheduler, fuse and encfs ...

i have no quick ideas - the behavior you are seeing is quite unexpected.
Could you try the current sched-devel code:

http://redhat.com/~mingo/cfs-scheduler/devel/sched-devel-combo-v2.6.23.patch

since this version of CFS does various things differently then the one
in v2.6.23, lets see whether perturbing it makes any difference to your
throughput.

you could also try the scheduler backport to v2.6.22.10, at:

http://redhat.com/~mingo/cfs-scheduler/

that would establish whether it's the changes in scheduling that cause
this or something else. Plus please enable CONFIG_SCHED_DEBUG and
CONFIG_SCHEDSTATS and run this debug script while such a transfer is
going on:

http://people.redhat.com/mingo/cfs-scheduler/tools/cfs-debug-info.sh

and send me the resulting file.

Ingo
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