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Re: [Xen-devel] [PATCH 0/3] gcc-plugins: Introduce stackinit plugin
- To: Kees Cook <keescook@xxxxxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx
- From: Alexander Popov <alex.popov@xxxxxxxxx>
- Date: Tue, 29 Jan 2019 03:12:24 +0300
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- Cc: dev@xxxxxxxxxxxxxxx, Matthew Wilcox <willy@xxxxxxxxxxxxx>, William Kucharski <william.kucharski@xxxxxxxxxx>, Jann Horn <jannh@xxxxxxxxxx>, Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>, netdev@xxxxxxxxxxxxxxx, intel-gfx@xxxxxxxxxxxxxxxxxxxxx, linux-usb@xxxxxxxxxxxxxxx, Jeff Kirsher <jeffrey.t.kirsher@xxxxxxxxx>, dri-devel@xxxxxxxxxxxxxxxxxxxxx, linux-mm@xxxxxxxxx, linux-security-module@xxxxxxxxxxxxxxx, kernel-hardening@xxxxxxxxxxxxxxxxxx, intel-wired-lan@xxxxxxxxxxxxxxxx, Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>, linux-fsdevel@xxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx, Laura Abbott <labbott@xxxxxxxxxx>, linux-kbuild@xxxxxxxxxxxxxxx, Edwin Zimmerman <edwin@xxxxxxxxxxxxxxxxx>
- Delivery-date: Tue, 29 Jan 2019 06:01:57 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
- Openpgp: preference=signencrypt
On 23.01.2019 14:03, Kees Cook wrote:
> This adds a new plugin "stackinit" that attempts to perform unconditional
> initialization of all stack variables
Hello Kees! Hello everyone!
I was curious about the performance impact of the initialization of all stack
variables. So I did a very brief test with this plugin on top of 4.20.5.
hackbench on Intel Core i7-4770 showed ~0.7% slowdown.
hackbench on Kirin 620 (ARM Cortex-A53 Octa-core 1.2GHz) showed ~1.3% slowdown.
This test involves the kernel scheduler and allocator. I can't say whether they
use stack aggressively. Maybe performance tests of other subsystems (e.g.
network subsystem) can show different numbers. Did you try?
I've heard a hypothesis that the initialization of all stack variables would
pollute CPU caches, which is critical for some types of computations. Maybe some
micro-benchmarks can disprove/confirm that?
Thanks!
Best regards,
Alexander
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