From: Rusty Russell <rusty@rustcorp.com.au>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
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>, 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>
Subject: Re: [PATCH 4/4] virtio_ring: unify direct/indirect code paths.
Date: Thu, 29 May 2014 20:35:58 +0930 [thread overview]
Message-ID: <87iooo7skp.fsf@rustcorp.com.au> (raw)
In-Reply-To: <20140529075256.GZ30445@twins.programming.kicks-ass.net>
Peter Zijlstra <peterz@infradead.org> writes:
> On Thu, May 29, 2014 at 04:56:45PM +0930, Rusty Russell wrote:
>> Before:
>> gcc 4.8.2: virtio_blk: stack used = 392
>> gcc 4.6.4: virtio_blk: stack used = 480
>>
>> After:
>> gcc 4.8.2: virtio_blk: stack used = 408
>> gcc 4.6.4: virtio_blk: stack used = 432
>
> Is it worth it to make the good compiler worse? People are going to use
> the newer GCC more as time goes on anyhow.
No, but it's only 16 bytes of stack loss for a simplicity win:
virtio_ring.c | 120 +++++++++++++++++++++-------------------------------------
1 file changed, 45 insertions(+), 75 deletions(-)
Cheers,
Rusty.
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WARNING: multiple messages have this Message-ID (diff)
From: Rusty Russell <rusty@rustcorp.com.au>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
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>, 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>
Subject: Re: [PATCH 4/4] virtio_ring: unify direct/indirect code paths.
Date: Thu, 29 May 2014 20:35:58 +0930 [thread overview]
Message-ID: <87iooo7skp.fsf@rustcorp.com.au> (raw)
In-Reply-To: <20140529075256.GZ30445@twins.programming.kicks-ass.net>
Peter Zijlstra <peterz@infradead.org> writes:
> On Thu, May 29, 2014 at 04:56:45PM +0930, Rusty Russell wrote:
>> Before:
>> gcc 4.8.2: virtio_blk: stack used = 392
>> gcc 4.6.4: virtio_blk: stack used = 480
>>
>> After:
>> gcc 4.8.2: virtio_blk: stack used = 408
>> gcc 4.6.4: virtio_blk: stack used = 432
>
> Is it worth it to make the good compiler worse? People are going to use
> the newer GCC more as time goes on anyhow.
No, but it's only 16 bytes of stack loss for a simplicity win:
virtio_ring.c | 120 +++++++++++++++++++++-------------------------------------
1 file changed, 45 insertions(+), 75 deletions(-)
Cheers,
Rusty.
next prev parent reply other threads:[~2014-05-29 11:09 UTC|newest]
Thread overview: 205+ 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 ` Minchan Kim
2014-05-28 6:53 ` [RFC 2/2] x86_64: expand kernel stack to 16K Minchan Kim
2014-05-28 6:53 ` Minchan Kim
2014-05-28 8:37 ` Dave Chinner
2014-05-28 8:37 ` Dave Chinner
2014-05-28 8:37 ` Dave Chinner
2014-05-28 9:13 ` Dave Chinner
2014-05-28 9:13 ` Dave Chinner
2014-05-28 9:13 ` Dave Chinner
2014-05-28 16:06 ` Johannes Weiner
2014-05-28 16:06 ` Johannes Weiner
2014-05-28 16:06 ` Johannes Weiner
2014-05-28 21:55 ` Dave Chinner
2014-05-28 21:55 ` Dave Chinner
2014-05-28 21:55 ` Dave Chinner
2014-05-29 6:06 ` Minchan Kim
2014-05-29 6:06 ` Minchan Kim
2014-05-29 6:06 ` Minchan Kim
2014-05-28 9:04 ` Michael S. Tsirkin
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 2:44 ` Steven Rostedt
2014-05-29 4:11 ` Minchan Kim
2014-05-29 4:11 ` Minchan Kim
2014-05-29 2:47 ` Rusty Russell
2014-05-29 2:47 ` Rusty Russell
2014-05-29 4:10 ` virtio_ring stack usage Rusty Russell
2014-05-28 9:27 ` [RFC 2/2] x86_64: expand kernel stack to 16K Borislav Petkov
2014-05-29 13:23 ` One Thousand Gnomes
2014-05-29 13:23 ` One Thousand Gnomes
2014-05-28 14:14 ` Steven Rostedt
2014-05-28 14:14 ` Steven Rostedt
2014-05-28 14:23 ` H. Peter Anvin
2014-05-28 14:23 ` H. Peter Anvin
2014-05-28 22:11 ` Dave Chinner
2014-05-28 22:11 ` Dave Chinner
2014-05-28 22:42 ` H. Peter Anvin
2014-05-28 22:42 ` H. Peter Anvin
2014-05-28 23:17 ` Dave Chinner
2014-05-28 23:17 ` Dave Chinner
2014-05-28 23:21 ` H. Peter Anvin
2014-05-28 23:21 ` H. Peter Anvin
2014-05-28 15:43 ` Richard Weinberger
2014-05-28 15:43 ` Richard Weinberger
2014-05-28 16:08 ` Steven Rostedt
2014-05-28 16:08 ` Steven Rostedt
2014-05-28 16:11 ` Richard Weinberger
2014-05-28 16:11 ` Richard Weinberger
2014-05-28 16:13 ` Linus Torvalds
2014-05-28 16:13 ` Linus Torvalds
2014-05-28 16:09 ` Linus Torvalds
2014-05-28 16:09 ` Linus Torvalds
2014-05-28 22:31 ` Dave Chinner
2014-05-28 22:31 ` Dave Chinner
2014-05-28 22:41 ` Linus Torvalds
2014-05-28 22:41 ` Linus Torvalds
2014-05-29 1:30 ` Dave Chinner
2014-05-29 1:30 ` Dave Chinner
2014-05-29 1:58 ` Dave Chinner
2014-05-29 1:58 ` Dave Chinner
2014-05-29 2:51 ` Linus Torvalds
2014-05-29 2:51 ` Linus Torvalds
2014-05-29 23:36 ` Minchan Kim
2014-05-29 23:36 ` Minchan Kim
2014-05-30 0:05 ` Linus Torvalds
2014-05-30 0:20 ` Minchan Kim
2014-05-30 0:20 ` Minchan Kim
2014-05-30 0:31 ` Linus Torvalds
2014-05-30 0:31 ` Linus Torvalds
2014-05-30 0:50 ` Minchan Kim
2014-05-30 0:50 ` Minchan Kim
2014-05-30 1:24 ` Linus Torvalds
2014-05-30 1:24 ` Linus Torvalds
2014-05-30 1:58 ` Dave Chinner
2014-05-30 1:58 ` Dave Chinner
2014-05-30 2:13 ` Linus Torvalds
2014-05-30 2:13 ` Linus Torvalds
2014-05-30 6:21 ` Minchan Kim
2014-05-30 6:21 ` Minchan Kim
2014-05-30 1:30 ` Linus Torvalds
2014-05-30 1:30 ` Linus Torvalds
2014-05-30 0:15 ` Dave Chinner
2014-05-30 0:15 ` Dave Chinner
2014-05-30 2:12 ` Minchan Kim
2014-05-30 2:12 ` Minchan Kim
2014-05-30 4:37 ` Linus Torvalds
2014-05-30 4:37 ` Linus Torvalds
2014-05-31 1:45 ` Linus Torvalds
2014-05-31 1:45 ` Linus Torvalds
2014-05-30 6:12 ` Minchan Kim
2014-05-30 6:12 ` Minchan Kim
2014-06-03 13:28 ` Rasmus Villemoes
2014-06-03 13:28 ` Rasmus Villemoes
2014-06-03 19:04 ` Linus Torvalds
2014-06-03 19:04 ` Linus Torvalds
2014-06-10 12:29 ` [PATCH 0/2] Per-task wait_queue_t Rasmus Villemoes
2014-06-10 12:29 ` [PATCH 1/2] wait: Introduce per-task wait_queue_t Rasmus Villemoes
2014-06-11 15:16 ` Oleg Nesterov
2014-06-10 12:29 ` [PATCH 2/2] wait: Use the per-task wait_queue_t in ___wait_event macro Rasmus Villemoes
2014-06-10 15:50 ` [PATCH 0/2] Per-task wait_queue_t Peter Zijlstra
2014-06-12 21:46 ` Rasmus Villemoes
2014-05-29 2:42 ` [RFC 2/2] x86_64: expand kernel stack to 16K Linus Torvalds
2014-05-29 2:42 ` Linus Torvalds
2014-05-29 5:14 ` H. Peter Anvin
2014-05-29 5:14 ` H. Peter Anvin
2014-05-29 6:01 ` Rusty Russell
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 ` Rusty Russell
2014-05-29 7:26 ` [PATCH 1/4] Hack: measure stack taken by vring from virtio_blk Rusty Russell
2014-05-29 7:26 ` Rusty Russell
2014-05-29 15:39 ` Linus Torvalds
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 7:26 ` Rusty Russell
2014-05-29 10:07 ` Michael S. Tsirkin
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 7:26 ` Rusty Russell
2014-05-29 11:18 ` Michael S. Tsirkin
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 7:26 ` Rusty Russell
2014-05-29 7:52 ` Peter Zijlstra
2014-05-29 11:05 ` Rusty Russell [this message]
2014-05-29 11:05 ` Rusty Russell
2014-05-29 11:33 ` Michael S. Tsirkin
2014-05-29 11:33 ` Michael S. Tsirkin
2014-05-29 11:29 ` Michael S. Tsirkin
2014-05-29 11:29 ` Michael S. Tsirkin
2014-05-30 2:37 ` Rusty Russell
2014-05-30 2:37 ` Rusty Russell
2014-05-30 6:21 ` Rusty Russell
2014-05-29 7:41 ` virtio ring cleanups, which save stack on older gcc Minchan Kim
2014-05-29 7:41 ` Minchan Kim
2014-05-29 10:39 ` Dave Chinner
2014-05-29 10:39 ` Dave Chinner
2014-05-29 11:08 ` Rusty Russell
2014-05-29 11:08 ` Rusty Russell
2014-05-29 23:45 ` Minchan Kim
2014-05-29 23:45 ` Minchan Kim
2014-05-30 1:06 ` Minchan Kim
2014-05-30 1:06 ` Minchan Kim
2014-05-30 6:56 ` Rusty Russell
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 7:26 ` Dave Chinner
2014-05-29 15:24 ` Linus Torvalds
2014-05-29 15:24 ` Linus Torvalds
2014-05-29 23:40 ` Minchan Kim
2014-05-29 23:40 ` Minchan Kim
2014-05-29 23:53 ` Dave Chinner
2014-05-29 23:53 ` Dave Chinner
2014-05-30 0:06 ` Dave Jones
2014-05-30 0:06 ` Dave Jones
2014-05-30 0:21 ` Dave Chinner
2014-05-30 0:21 ` Dave Chinner
2014-05-30 0:29 ` Dave Jones
2014-05-30 0:29 ` Dave Jones
2014-05-30 0:32 ` Minchan Kim
2014-05-30 0:32 ` Minchan Kim
2014-05-30 1:34 ` Dave Chinner
2014-05-30 1:34 ` Dave Chinner
2014-05-30 15:25 ` H. Peter Anvin
2014-05-30 15:25 ` H. Peter Anvin
2014-05-30 15:41 ` Linus Torvalds
2014-05-30 15:41 ` Linus Torvalds
2014-05-30 15:52 ` H. Peter Anvin
2014-05-30 15:52 ` H. Peter Anvin
2014-05-30 16:06 ` Linus Torvalds
2014-05-30 16:06 ` Linus Torvalds
2014-05-30 17:24 ` Dave Hansen
2014-05-30 17:24 ` Dave Hansen
2014-05-30 18:12 ` H. Peter Anvin
2014-05-30 18:12 ` H. Peter Anvin
2014-10-21 2:00 ` Dave Jones
2014-10-21 4:59 ` Andy Lutomirski
2014-05-30 9:48 ` Richard Weinberger
2014-05-30 9:48 ` Richard Weinberger
2014-05-30 15:36 ` Linus Torvalds
2014-05-30 15:36 ` Linus Torvalds
2014-05-31 2:06 ` Jens Axboe
2014-05-31 2:06 ` Jens Axboe
2014-06-02 22:59 ` Dave Chinner
2014-06-02 22:59 ` Dave Chinner
2014-06-03 13:02 ` Konstantin Khlebnikov
2014-06-03 13:02 ` Konstantin Khlebnikov
2014-05-29 3:46 ` Minchan Kim
2014-05-29 3:46 ` Minchan Kim
2014-05-29 4:13 ` Linus Torvalds
2014-05-29 4:13 ` Linus Torvalds
2014-05-29 5:10 ` Minchan Kim
2014-05-29 5:10 ` Minchan Kim
2014-05-30 21:23 ` Andi Kleen
2014-05-30 21:23 ` Andi Kleen
2014-05-28 16:18 ` [PATCH 1/2] ftrace: print stack usage right before Oops Steven Rostedt
2014-05-28 16:18 ` Steven Rostedt
2014-05-29 3:52 ` Minchan Kim
2014-05-29 3:52 ` Minchan Kim
2014-05-29 3:01 ` Steven Rostedt
2014-05-29 3:01 ` Steven Rostedt
2014-05-29 3:49 ` Minchan Kim
2014-05-29 3:49 ` Minchan Kim
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