linux-kernel - Re: [RFC 2/2] x86_64: expand kernel stack to 16K

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Message-ID: <CA+55aFwHS2xErW6TgBHGR9JP0QZW9W7GSLec5WzbV+GGYFUu6A@mail.gmail.com>
Date:	Fri, 30 May 2014 09:06:03 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Dave Chinner <david@...morbit.com>,
	Minchan Kim <minchan@...nel.org>,
	Dave Jones <davej@...hat.com>, Jens Axboe <axboe@...nel.dk>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-mm <linux-mm@...ck.org>, Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Mel Gorman <mgorman@...e.de>, Rik van Riel <riel@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Hugh Dickins <hughd@...gle.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	"Michael S. Tsirkin" <mst@...hat.com>,
	Dave Hansen <dave.hansen@...el.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	PJ Waskiewicz <pjwaskiewicz@...il.com>
Subject: Re: [RFC 2/2] x86_64: expand kernel stack to 16K

On Fri, May 30, 2014 at 8:52 AM, H. Peter Anvin <hpa@...or.com> wrote:
>>
>> That said, it's still likely a non-production option due to the page
>> table games we'd have to play at fork/clone time.
>
> Still, seems much more tractable.

We might be able to make it more attractive by having a small
front-end cache of the 16kB allocations with the second page unmapped.
That would at least capture the common "lots of short-lived processes"
case without having to do kernel page table work.

               Linus
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