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Date: Wed, 25 Jan 2017 16:15:19 +0100 From: Arnd Bergmann <arnd@...db.de> To: Christoph Hellwig <hch@...radead.org> Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Steven Rostedt <rostedt@...dmis.org>, Nicolas Pitre <nico@...aro.org>, "Darrick J. Wong" <darrick.wong@...cle.com>, linux-xfs@...r.kernel.org, Dave Chinner <dchinner@...hat.com>, Brian Foster <bfoster@...hat.com>, Eric Sandeen <sandeen@...deen.net> Subject: Re: [PATCH] [RFC] xfs: work around unlikely() profiler glitch On Wed, Jan 25, 2017 at 4:09 PM, Christoph Hellwig <hch@...radead.org> wrote: > On Wed, Jan 25, 2017 at 03:08:10PM +0100, Arnd Bergmann wrote: >> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c >> index d22f7930eb75..dca3ddd737d4 100644 >> --- a/fs/xfs/libxfs/xfs_bmap.c >> +++ b/fs/xfs/libxfs/xfs_bmap.c >> @@ -3629,7 +3629,7 @@ xfs_bmap_btalloc( >> align = xfs_get_cowextsz_hint(ap->ip); >> else if (xfs_alloc_is_userdata(ap->datatype)) >> align = xfs_get_extsz_hint(ap->ip); >> - if (unlikely(align)) { >> + if (unlikely_notrace(align)) { >> error = xfs_bmap_extsize_align(mp, &ap->got, &ap->prev, >> align, 0, ap->eof, 0, ap->conv, >> &ap->offset, &ap->length); > > The unlikely calls on align in xfs_bmap_btalloc should simply be > removed. They aren't actually unlikely for many workloads. I have > a patch in my queue that I can expedite based on your report. That would defines help, thanks! I also noticed that my patch wouldn't work, as unlikely_notrace() is not defined unless we are actually tracing, so while it fixes some rare configurations, it breaks all the configurations that matter. Arnd
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