On 2014-09-03 21:18, Steven Hartland wrote:
----- Original Message ----- From: "Andriy Gapon" <a...@freebsd.org>
on 03/09/2014 23:22 Nikolai Lifanov said the following:
On 09/03/14 15:22, John Baldwin wrote:
On Wednesday, September 03, 2014 11:05:04 AM Nikolai Lifanov wrote:
On 09/03/14 04:09, Steven Hartland wrote:
I'm looking to MFC this change so wanted to check if
anyone had an final feedback / objections?
I know we currently have Alan's feedback on changing
the #ifdef __i386__ to #ifndef UMA_MD_SMALL_ALLOC
which sounds sensible but waiting Peter to comment on.
Regards
Steve
I have no technical input, but this change improves ARC usefulness
for
me quite a bit. I would like to see the improvement in 10-STABLE.
Can you verify that the current 10-STABLE (as of today) with all the
various pagedaemon fixes still has ARC issues for your workload?
It doesn't have any issues, but I noticed the improvement on CURRENT.
I
observed that just after this change, my package builder is much more
likely to retain MFU and not evict useful things from there (the port
tree) after large builds.
However, I run a lot more 10.0-RELEASE than CURRENT and I would like
to
see this improvement release-bound.
I would be happy to test this on 10-STABLE if you think that this is
relevant.
As noted before, unfortunately, this commit (plus its fixups) contains
at least
two related but distinct changes. So, to separate the wheat from the
chaff,
could you please try to comment out the following block in
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c, function
arc_reclaim_needed:
if (kmem_free_count() < zfs_arc_free_target) {
DTRACE_PROBE2(arc__reclaim_freetarget, uint64_t,
kmem_free_count(), uint64_t, zfs_arc_free_target);
return (1);
}
Alternatively, I think that the same effect can be achieved by setting
sysctl
vfs.zfs.arc_free_target to the same value as vm.stats.vm.v_free_min.
Thats correct that would achieve the same thing.
It's interesting to me whether you would still see the better
performance or if
that improvement would be undone.
Indeed that would be interesting, but we might find that its quite
memory size
dependent given the scaling so confirming HW details would be nice too.
I'd also be interested to know who wins the free race between the VM
and ARC
when using that value.
For those following this thread but not the review, I've added some
additional
information there which you might be interested in:
https://reviews.freebsd.org/D702
Regards
Steve
I had time to re-test both the "stock" condition after the improvements
and the condition in which
vfs.zfs.arc_free_target=vm.stats.vm.v_free_min. It seems that MFU is
more likely to be reduced in the second case.
- Nikolai Lifanov
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