svn commit: r326619 - stable/11/sys/cddl/contrib/opensolaris/uts/common/fs/zfs

[Baptiste Daroussin]

On Thu, Dec 14, 2017 at 05:52:15AM +1100, Peter Jeremy wrote:
> On 2017-Dec-06 10:01:02 +0000, Baptiste Daroussin <bapt at FreeBSD.org> wrote:
> >Author: bapt
> >Date: Wed Dec  6 10:01:02 2017
> >New Revision: 326619
> >URL: https://svnweb.freebsd.org/changeset/base/326619
> >
> >Log:
> >  MFC r325851:
> >  
> >  remove the poor emulation of the IllumOS needfree global variable to prevent
> >  the ARC reclaim thread running longer than needed.
> >  
> 
> This change appears to break the backpressure mechanism that forces
> ARC to release wired memory.  Running FreeBSD/amd64 r326743, I found
> that my system was thrashing badly with almost all memory (~31GB out
> of 32GB) wired (including 19GB ARC, 7GB VBox guests).  Running a tool
> that just allocates and dirties a large amount of memory had no effect
> on the ARC size.  Reverting this change only restores normal behaviour
> where ARC will shrink under pressure.
> 
> My ZFS boot tunables are:
> vfs.zfs.arc_max="24G"
> vfs.zfs.arc_meta_limit="12G"
> 

You are running an issue on head? or on stable/11? Given you are reporting the
issue on the MFC commit

Best regards,
Bapt
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