ZFS (ARC) performance regression in r321610

[Yamagi Burmeister]

Hi,
my patch was committed this morning. If you're on 12-CURRENT you can
just set vfs.zfs.abd_scatter_enabled to 0. On other branches the
easiest way to make the change permanent is to edit
sys/cddl/contrib/opensolaris/uts/common/fszfs/abd.c and change
zfs_abd_scatter_enabled (on 11.2 it's in line 141) from B_TRUE to
B_FALSE. Then rebuild the kernel, reboot and you're done.

Regards,
Yamagi

On Wed, 29 Aug 2018 11:45:45 +0200
rainer at ultra-secure.de wrote:

> Am 2018-08-27 16:19, schrieb Lev Serebryakov:
> > On 27.08.2018 16:47, Yamagi Burmeister wrote:
> > 
> >> With this program I was able to bisect the source and identify commit
> >> r321610 (MFV r318946: 8021 ARC buf data scatter-ization) as the 
> >> culprit:
> >> https://svnweb.freebsd.org/base?view=revision&revision=321610
> >  You could try to set "zfs_abd_scatter_enabled = 0" via kgdb and repeat
> > tests to be sure, that this code is a problem.
> > 
> >  BTW, it is not clear, that FreeBSD needs this at all.
> 
> 
> Hi,
> 
> how exactly do I do this?
> 
> 
> 
> Best Regards
> Rainer


-- 
Homepage: https://www.yamagi.org
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