Re: [PATCHv2 2/2] mm/page_poisoning.c: Allow for zero poisoning

From	Pavel Machek <pavel@denx.de>
Newsgroups	linux.kernel
Subject	Re: [PATCHv2 2/2] mm/page_poisoning.c: Allow for zero poisoning
Date	2016-01-30 16:40 +0100
Message-ID	<qWFMZ-5uf-3@gated-at.bofh.it> (permalink)
References	<qW78C-4lQ-15@gated-at.bofh.it> <qW78C-4lQ-23@gated-at.bofh.it> <qWeMO-1un-11@gated-at.bofh.it> <qWoVP-MS-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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Hi!

> >>By default, page poisoning uses a poison value (0xaa) on free. If this
> >>is changed to 0, the page is not only sanitized but zeroing on alloc
> >>with __GFP_ZERO can be skipped as well. The tradeoff is that detecting
> >>corruption from the poisoning is harder to detect. This feature also
> >>cannot be used with hibernation since pages are not guaranteed to be
> >>zeroed after hibernation.
> >
> >So... this makes kernel harder to debug for performance advantage...?
> >If so.. how big is the performance advantage?

> 
> The performance advantage really depends on the benchmark you are
> running.

You are trying to improve performance, so you should publish at least
one benchmark where it helps.

Alternatively, quote kernel build times with and without the
patch.

If it speeds kernel compile twice, I guess I may even help with
hibernation support. If it makes kernel compile faster by .00000034%
(or slows it down), we should probably simply ignore this patch.

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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[PATCHv2 0/2] Sanitization of buddy pages Laura Abbott <labbott@fedoraproject.org> - 2016-01-29 03:40 +0100
  [PATCHv2 2/2] mm/page_poisoning.c: Allow for zero poisoning Laura Abbott <labbott@fedoraproject.org> - 2016-01-29 03:40 +0100
    Re: [PATCHv2 2/2] mm/page_poisoning.c: Allow for zero poisoning "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-01-29 05:00 +0100
    Re: [PATCHv2 2/2] mm/page_poisoning.c: Allow for zero poisoning Kees Cook <keescook@chromium.org> - 2016-01-29 05:50 +0100
      Re: [PATCHv2 2/2] mm/page_poisoning.c: Allow for zero poisoning Laura Abbott <labbott@redhat.com> - 2016-01-29 22:40 +0100
    Re: [PATCHv2 2/2] mm/page_poisoning.c: Allow for zero poisoning Pavel Machek <pavel@denx.de> - 2016-01-29 11:50 +0100
      Re: [PATCHv2 2/2] mm/page_poisoning.c: Allow for zero poisoning Laura Abbott <labbott@redhat.com> - 2016-01-29 22:40 +0100
        Re: [PATCHv2 2/2] mm/page_poisoning.c: Allow for zero poisoning Pavel Machek <pavel@denx.de> - 2016-01-30 16:40 +0100

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