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Date: Thu, 29 May 2014 08:39:11 -0700
Message-ID: <CA+55aFzybuwti5z=uGXxibLqyDwQpPE88bN4cL5YQwpfb7aMbw@mail.gmail.com>
Subject: Re: [PATCH 1/4] Hack: measure stack taken by vring from virtio_blk
From: Linus Torvalds <torvalds@linux-foundation.org>
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To: Rusty Russell <rusty@rustcorp.com.au>
Cc: Dave Chinner <david@fromorbit.com>, Jens Axboe <axboe@kernel.dk>, Minchan Kim <minchan@kernel.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Andrew Morton <akpm@linux-foundation.org>, linux-mm <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>, "Michael S. Tsirkin" <mst@redhat.com>, Dave Hansen <dave.hansen@intel.com>, Steven Rostedt <rostedt@goodmis.org>

On Thu, May 29, 2014 at 12:26 AM, Rusty Russell <rusty@rustcorp.com.au> wrote:
> Results (x86-64, Minchan's .config):
>
> gcc 4.8.2: virtio_blk: stack used = 392
> gcc 4.6.4: virtio_blk: stack used = 528

I wonder if that's just random luck (although 35% more stack use seems
to be bigger than "random" - that's quite a big difference), or
whether the gcc guys are aware of having fixed some major stack spill
issue.

But yeah, Minchan uses gcc 4.6.3 according to one of his emails, so
_part_ of his stack smashing is probably due to compiler version.

                  Linus

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