From: der.herr@hofr.at (Nicholas Mc Guire)
To: kernelnewbies@lists.kernelnewbies.org
Subject: unlikely compiler flag propagation
Date: Wed, 18 Feb 2015 20:02:14 +0100 [thread overview]
Message-ID: <20150218190214.GA17616@opentech.at> (raw)
In-Reply-To: <24781.1424285845@turing-police.cc.vt.edu>
On Wed, 18 Feb 2015, Valdis.Kletnieks at vt.edu wrote:
> On Wed, 18 Feb 2015 19:38:01 +0100, Nicholas Mc Guire said:
> > On Wed, 18 Feb 2015, Greg KH wrote:
>
> > interesting - would you have a reference to some talk/paper/data/... ?
>
> Test for yourself :)
>
> config PROFILE_ANNOTATED_BRANCHES
> bool "Trace likely/unlikely profiler"
> select TRACE_BRANCH_PROFILING
> help
> This tracer profiles all likely and unlikely macros
> in the kernel. It will display the results in:
>
> /sys/kernel/debug/tracing/trace_stat/branch_annotated
>
> Note: this will add a significant overhead; only turn this
> on if you need to profile the system's use of these macros.
>
was not aware of that - many thanks !
I do assume that such a claim of 90% not being effective would
not be based on testing some single system but based on a much
wider basis so that data would be interesting to see data from
different clases of systems.
thx!
hofrat
next prev parent reply other threads:[~2015-02-18 19:02 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-18 18:09 unlikely compiler flag propagation Matthias Brugger
2015-02-18 18:24 ` Greg KH
2015-02-18 18:35 ` Matthias Brugger
2015-02-18 19:02 ` Greg KH
2015-02-18 18:38 ` Nicholas Mc Guire
2015-02-18 18:57 ` Valdis.Kletnieks at vt.edu
2015-02-18 19:02 ` Nicholas Mc Guire [this message]
2015-02-19 11:34 ` Anupam Kapoor
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