linux-kernel - Re: [PATCH v2] kbuild: use -flive-patching when CONFIG

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Date:   Tue, 9 Apr 2019 09:36:07 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     Miroslav Benes <mbenes@...e.cz>, yamada.masahiro@...ionext.com,
        michal.lkml@...kovi.net, jikos@...nel.org, joe.lawrence@...hat.com,
        ggherdovich@...e.cz, linux-kbuild@...r.kernel.org,
        live-patching@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] kbuild: use -flive-patching when CONFIG_LIVEPATCH is
 enabled

On Thu 2019-04-04 15:18:55, Josh Poimboeuf wrote:
> On Thu, Apr 04, 2019 at 08:44:11PM +0200, Miroslav Benes wrote:
> > GCC 9 introduces a new option, -flive-patching. It disables certain
> > optimizations which could make a compilation unsafe for later live
> > patching of the running kernel.
> > 
> > The option is used only if CONFIG_LIVEPATCH is enabled and $(CC)
> > supports it.
> > 
> > Performance impact of the option was measured on three different
> > Intel machines - two bigger NUMA boxes and one smaller UMA box. Kernel
> > intensive (IO, scheduling, networking) benchmarks were selected, plus a
> > set of HPC workloads from NAS Parallel Benchmark. The tests were done on
> > upstream kernel 5.0-rc8 with openSUSE Leap 15.0 userspace.
> > 
> > The majority of the tests is unaffected. The only significant exception
> > is the scheduler section which suffers 1-3% degradation.
> > 
> > Evaluated-by: Giovanni Gherdovich <ggherdovich@...e.cz>
> > Signed-off-by: Miroslav Benes <mbenes@...e.cz>
> > ---
> > The patch is based on master branch of the livepatching tree on
> > git.kernel.org.
> > 
> > Many thanks to Giovanni who ran the whole testing campaign and analyzed
> > the results. I archived the dashboard and detailed data. If anyone is
> > interested, we could probably set up a public website somewhere.
> 
> Acked-by: Josh Poimboeuf <jpoimboe@...hat.com>

I have committed the patch into the branch for-5.2/core.

Best Regards,
Petr