From: Kees Cook <kees@kernel.org>
To: kernel test robot <oliver.sang@intel.com>
Cc: oe-lkp@lists.linux.dev, lkp@intel.com,
linux-kernel@vger.kernel.org,
"Thomas Weißschuh" <linux@weissschuh.net>,
"Nilay Shroff" <nilay@linux.ibm.com>,
"Yury Norov" <yury.norov@gmail.com>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
linux-hardening@vger.kernel.org
Subject: Re: [linus:master] [fortify] 239d87327d: vm-scalability.throughput 17.3% improvement
Date: Thu, 9 Jan 2025 12:38:04 -0800 [thread overview]
Message-ID: <202501091236.E3EDA2188@keescook> (raw)
In-Reply-To: <202501090850.F23EBEBC5B@keescook>
On Thu, Jan 09, 2025 at 08:51:44AM -0800, Kees Cook wrote:
> On Thu, Jan 09, 2025 at 02:57:58PM +0800, kernel test robot wrote:
> > kernel test robot noticed a 17.3% improvement of vm-scalability.throughput on:
> >
> > commit: 239d87327dcd361b0098038995f8908f3296864f ("fortify: Hide run-time copy size from value range tracking")
> > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
>
> Well that is unexpected. There should be no binary output difference
> with that patch. I will investigate...
It looks like hiding the size value from GCC has the side-effect of
breaking memcpy inlining in many places. I would expect this to make
things _slower_, though. O_o
--
Kees Cook
next prev parent reply other threads:[~2025-01-09 20:38 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-09 6:57 [linus:master] [fortify] 239d87327d: vm-scalability.throughput 17.3% improvement kernel test robot
2025-01-09 16:51 ` Kees Cook
2025-01-09 20:38 ` Kees Cook [this message]
2025-01-09 20:52 ` Mateusz Guzik
2025-01-09 21:12 ` Kees Cook
2025-01-09 22:01 ` Mateusz Guzik
2025-01-10 16:58 ` Kees Cook
2025-01-10 19:14 ` Mateusz Guzik
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