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Date: Wed, 28 May 2014 09:13:51 -0700
Message-ID: <CA+55aFwK5PnWonJZUA0O0dZp=k6RL7gRE5rjSTpxwcbS8ydkyQ@mail.gmail.com>
Subject: Re: [RFC 2/2] x86_64: expand kernel stack to 16K
From: Linus Torvalds <torvalds@linux-foundation.org>
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To: Steven Rostedt <rostedt@goodmis.org>
Cc: Richard Weinberger <richard.weinberger@gmail.com>, Minchan Kim <minchan@kernel.org>, LKML <linux-kernel@vger.kernel.org>, Andrew Morton <akpm@linux-foundation.org>, "linux-mm@kvack.org" <linux-mm@kvack.org>, "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@kernel.org>, Peter Zijlstra <a.p.zijlstra@chello.nl>, Mel Gorman <mgorman@suse.de>, Rik van Riel <riel@redhat.com>, Johannes Weiner <hannes@cmpxchg.org>, Hugh Dickins <hughd@google.com>, Rusty Russell <rusty@rustcorp.com.au>, "Michael S. Tsirkin" <mst@redhat.com>, Dave Hansen <dave.hansen@intel.com>

On Wed, May 28, 2014 at 9:08 AM, Steven Rostedt <rostedt@goodmis.org> wrote:
>
> What performance impact are you looking for? Now if the system is short
> on memory, it would probably cause issues in creating tasks.

It doesn't necessarily need to be short on memory, it could just be
fragmented. But a page order of 2 should still be ok'ish.

That said, this is definitely not a rc7 issue. I'd *much* rather
disable swap from direct reclaim, although that kind of patch too
would be a "can Minchan test it, we can put it in the next merge
window and then backport it if we don't have issues".

I see that Johannes already did a patch for that (and this really
_has_ come up before), although I'd skip the WARN_ON_ONCE() part
except for perhaps Minchan testing it.

               Linus

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