[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20090528090836.GB6715@elte.hu>
Date: Thu, 28 May 2009 11:08:36 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Alan Cox <alan@...rguk.ukuu.org.uk>
Cc: Rik van Riel <riel@...hat.com>,
"Larry H." <research@...reption.com>, linux-kernel@...r.kernel.org,
Linus Torvalds <torvalds@...l.org>, linux-mm@...ck.org,
Ingo Molnar <mingo@...hat.com>, pageexec@...email.hu,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [patch 0/5] Support for sanitization flag in low-level page
allocator
* Alan Cox <alan@...rguk.ukuu.org.uk> wrote:
> > > As for being swapped out - I do not believe that kernel stacks can
> > > ever be swapped out in Linux.
> >
> > yes, i referred to that as an undesirable option - because it slows
> > down pthread_create() quite substantially.
> >
> > This needs before/after pthread_create() benchmark results.
>
> kernel stacks can end up places you don't expect on hypervisor
> based systems.
>
> In most respects the benchmarks are pretty irrelevant - wiping
> stuff has a performance cost, but its the sort of thing you only
> want to do when you have a security requirement that needs it. At
> that point the performance is secondary.
Bechmarks, of course, are not irrelevant _at all_.
So i'm asking for this "clear kernel stacks on freeing" aspect to be
benchmarked thoroughly, as i expect it to have a negative impact -
otherwise i'm NAK-ing this. Please Cc: me to measurements results.
Thanks,
Ingo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists