From: Linus Torvalds <torvalds@linux-foundation.org>
To: Minchan Kim <minchan@kernel.org>
Cc: 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>,
Rusty Russell <rusty@rustcorp.com.au>,
"Michael S. Tsirkin" <mst@redhat.com>,
Dave Hansen <dave.hansen@intel.com>,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [RFC 2/2] x86_64: expand kernel stack to 16K
Date: Wed, 28 May 2014 21:13:15 -0700 [thread overview]
Message-ID: <CA+55aFyoT1xuM-HsZ4GKt=FfDYs76oD7U-RBkZn-2PErj6ZZVw@mail.gmail.com> (raw)
In-Reply-To: <20140529034625.GB10092@bbox>
On Wed, May 28, 2014 at 8:46 PM, Minchan Kim <minchan@kernel.org> wrote:
>
> Yes. For example, with mark __alloc_pages_slowpath noinline_for_stack,
> we can reduce 176byte.
Well, but it will then call that __alloc_pages_slowpath() function,
which has a 176-byte stack frame.. Plus the call frame.
Now, that only triggers for when the initial "__GFP_HARDWALL" case
fails, but that's exactly what happens when we do need to do direct
reclaim.
That said, I *have* seen cases where the gcc spill code got really
confused, and simplifying the function (by not inlining excessively)
actually causes a truly smaller stack overall, despite the actual call
frames etc. But I think the gcc people fixed the kinds of things that
caused *that* kind of stack slot explosion.
And avoiding inlining can end up resulting in less stack, if the
really deep parts don't happen to go through that function that got
inlined (ie any call chain that wouldn't have gone through that
"slowpath" function at all).
But in this case, __alloc_pages_slowpath() is where we end up doing
the actual direct reclaim anyway, so just uninlining doesn't actually
help. Although it would probably make the asm code more readable ;)
Linus
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next prev parent reply other threads:[~2014-05-29 4:13 UTC|newest]
Thread overview: 97+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-28 6:53 [PATCH 1/2] ftrace: print stack usage right before Oops Minchan Kim
2014-05-28 6:53 ` [RFC 2/2] x86_64: expand kernel stack to 16K Minchan Kim
2014-05-28 8:37 ` Dave Chinner
2014-05-28 9:13 ` Dave Chinner
2014-05-28 16:06 ` Johannes Weiner
2014-05-28 21:55 ` Dave Chinner
2014-05-29 6:06 ` Minchan Kim
2014-05-28 9:04 ` Michael S. Tsirkin
2014-05-29 1:09 ` Minchan Kim
2014-05-29 2:44 ` Steven Rostedt
2014-05-29 4:11 ` Minchan Kim
2014-05-29 2:47 ` Rusty Russell
2014-05-28 9:27 ` Borislav Petkov
2014-05-29 13:23 ` One Thousand Gnomes
2014-05-28 14:14 ` Steven Rostedt
2014-05-28 14:23 ` H. Peter Anvin
2014-05-28 22:11 ` Dave Chinner
2014-05-28 22:42 ` H. Peter Anvin
2014-05-28 23:17 ` Dave Chinner
2014-05-28 23:21 ` H. Peter Anvin
2014-05-28 15:43 ` Richard Weinberger
2014-05-28 16:08 ` Steven Rostedt
2014-05-28 16:11 ` Richard Weinberger
2014-05-28 16:13 ` Linus Torvalds
2014-05-28 16:09 ` Linus Torvalds
2014-05-28 22:31 ` Dave Chinner
2014-05-28 22:41 ` Linus Torvalds
2014-05-29 1:30 ` Dave Chinner
2014-05-29 1:58 ` Dave Chinner
2014-05-29 2:51 ` Linus Torvalds
2014-05-29 23:36 ` Minchan Kim
2014-05-30 0:05 ` Linus Torvalds
2014-05-30 0:20 ` Minchan Kim
2014-05-30 0:31 ` Linus Torvalds
2014-05-30 0:50 ` Minchan Kim
2014-05-30 1:24 ` Linus Torvalds
2014-05-30 1:58 ` Dave Chinner
2014-05-30 2:13 ` Linus Torvalds
2014-05-30 6:21 ` Minchan Kim
2014-05-30 1:30 ` Linus Torvalds
2014-05-30 0:15 ` Dave Chinner
2014-05-30 2:12 ` Minchan Kim
2014-05-30 4:37 ` Linus Torvalds
2014-05-31 1:45 ` Linus Torvalds
2014-05-30 6:12 ` Minchan Kim
2014-06-03 13:28 ` Rasmus Villemoes
2014-06-03 19:04 ` Linus Torvalds
2014-05-29 2:42 ` Linus Torvalds
2014-05-29 5:14 ` H. Peter Anvin
2014-05-29 6:01 ` Rusty Russell
2014-05-29 7:26 ` virtio ring cleanups, which save stack on older gcc Rusty Russell
2014-05-29 7:26 ` [PATCH 1/4] Hack: measure stack taken by vring from virtio_blk Rusty Russell
2014-05-29 15:39 ` Linus Torvalds
2014-05-29 7:26 ` [PATCH 2/4] virtio_net: pass well-formed sg to virtqueue_add_inbuf() Rusty Russell
2014-05-29 10:07 ` Michael S. Tsirkin
2014-05-29 7:26 ` [PATCH 3/4] virtio_ring: assume sgs are always well-formed Rusty Russell
2014-05-29 11:18 ` Michael S. Tsirkin
2014-05-29 7:26 ` [PATCH 4/4] virtio_ring: unify direct/indirect code paths Rusty Russell
2014-05-29 7:52 ` Peter Zijlstra
2014-05-29 11:05 ` Rusty Russell
2014-05-29 11:33 ` Michael S. Tsirkin
2014-05-29 11:29 ` Michael S. Tsirkin
2014-05-30 2:37 ` Rusty Russell
2014-05-29 7:41 ` virtio ring cleanups, which save stack on older gcc Minchan Kim
2014-05-29 10:39 ` Dave Chinner
2014-05-29 11:08 ` Rusty Russell
2014-05-29 23:45 ` Minchan Kim
2014-05-30 1:06 ` Minchan Kim
2014-05-30 6:56 ` Rusty Russell
2014-05-29 7:26 ` [RFC 2/2] x86_64: expand kernel stack to 16K Dave Chinner
2014-05-29 15:24 ` Linus Torvalds
2014-05-29 23:40 ` Minchan Kim
2014-05-29 23:53 ` Dave Chinner
2014-05-30 0:06 ` Dave Jones
2014-05-30 0:21 ` Dave Chinner
2014-05-30 0:29 ` Dave Jones
2014-05-30 0:32 ` Minchan Kim
2014-05-30 1:34 ` Dave Chinner
2014-05-30 15:25 ` H. Peter Anvin
2014-05-30 15:41 ` Linus Torvalds
2014-05-30 15:52 ` H. Peter Anvin
2014-05-30 16:06 ` Linus Torvalds
2014-05-30 17:24 ` Dave Hansen
2014-05-30 18:12 ` H. Peter Anvin
2014-05-30 9:48 ` Richard Weinberger
2014-05-30 15:36 ` Linus Torvalds
2014-05-31 2:06 ` Jens Axboe
2014-06-02 22:59 ` Dave Chinner
2014-06-03 13:02 ` Konstantin Khlebnikov
2014-05-29 3:46 ` Minchan Kim
2014-05-29 4:13 ` Linus Torvalds [this message]
2014-05-29 5:10 ` Minchan Kim
2014-05-30 21:23 ` Andi Kleen
2014-05-28 16:18 ` [PATCH 1/2] ftrace: print stack usage right before Oops Steven Rostedt
2014-05-29 3:52 ` Minchan Kim
2014-05-29 3:01 ` Steven Rostedt
2014-05-29 3:49 ` Minchan Kim
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