svn commit: r278040 - head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs

[Will Andrews]

On Sunday, February 1, 2015, Davide Italiano <davide at freebsd.org> wrote:

> On Mon, Feb 2, 2015 at 1:17 AM, Steven Hartland <smh at freebsd.org
> <javascript:;>> wrote:
> > Author: smh
> > Date: Mon Feb  2 00:17:36 2015
> > New Revision: 278040
> > URL: https://svnweb.freebsd.org/changeset/base/278040
> >
> > Log:
> >   Prevent inlining txg_quiesce
> >
> >   This allows dtrace to monitor the calls to txg_quiesce which can be
> really
> >   helpful.
> >
> >   Also standardise __noinline order for arc_kmem_reap_now.
> >
> >   Sponsored by: Multiplay
> >
> >
>
> I found this while I was at iXsystems, trying to port Richard Elling's
> arc statistics utility to FreeBSD.
> I do not disagree with the change in theory, but I never committed
> this because I was worried of performance penalty.
> Last time I checked Solaris/Illumos actually do not inline this
> function without any particular directive (I guess this is mostly due
> to difference in toolchain, in particular in the compiler), so it
> shouldn't be a big deal, but if you have time, do you mind to check
> the penalty introduced, if any, is negligible?
>

It should be negligible. The function is only called once per txg, which
generally is only supposed to happen about 1-0.2Hz.

--Will.