From: Rusty Russell <rusty@rustcorp.com.au>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>, Asias He <asias@redhat.com>,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org
Subject: Re: [PATCH 08/16] virtio_ring: virtqueue_add_outbuf / virtqueue_add_inbuf.
Date: Wed, 06 Mar 2013 17:03:42 +1100 [thread overview]
Message-ID: <87y5e19i9t.fsf@rustcorp.com.au> (raw)
In-Reply-To: <20130228070124.GD4743@redhat.com>
"Michael S. Tsirkin" <mst@redhat.com> writes:
>> Without the inline keywords, it doesn't inline virtqueue_add, and thus
>> sg_next_chained and sg_next_add aren't inlined:
>>
>> $ for i in `seq 50`; do /usr/bin/time --format=%U ./vringh_test --indirect --eventidx --parallel; done 2>&1 | stats --trim-outliers
>> Using CPUS 0 and 3
>> Guest: notified 39102-39145(39105), pinged 39060-39063(39063)
>> Host: notified 39060-39063(39063), pinged 19551-19581(19553)
>> 3.050000-3.220000(3.136875)
>>
>> With inline:
>>
>> $ for i in `seq 50`; do /usr/bin/time --format=%U ./vringh_test --indirect --eventidx --parallel; done 2>&1 | stats --trim-outliers
>> Using CPUS 0 and 3
>> Guest: notified 39084-39148(39099), pinged 39062-39063(39062)
>> Host: notified 39062-39063(39062), pinged 19542-19574(19550)
>> 2.940000-3.140000(3.014583)
>>
>> Cheers,
>> Rusty.
>
> Cool and did it actually unroll all loops?
Sorry for the delay in answering... I spent a day chasing red-herrings,
as my tests became limited by the vringh side, so optimizations on the
virtio side were having no effect :(
I'll answer a related question based on the current tree, where
virtio_add_outbuf (and virtio_add_inbuf) are the stars:
return virtqueue_add(vq, &sg, sg_next_arr, num, 0, 1, 0, data, gfp);
Ideally, gcc would eliminated the input-descriptor loop altogether (that
0 for in_sgs), and unroll the 1-iteration output-descriptor loop into
straightline code.
Which it seems to have done, by my reading of the asm (at least, for gcc
4.7 on 32-bit x86).
Cheers,
Rusty.
next prev parent reply other threads:[~2013-03-06 7:17 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-19 7:56 [PATCH 00/16] virtio ring rework Rusty Russell
2013-02-19 7:56 ` [PATCH 01/16] scatterlist: introduce sg_unmark_end Rusty Russell
2013-02-19 7:56 ` [PATCH 02/16] virtio_ring: virtqueue_add_sgs, to add multiple sgs Rusty Russell
2013-02-19 9:15 ` Wanlong Gao
2013-02-20 9:18 ` Asias He
2013-02-24 22:12 ` Michael S. Tsirkin
2013-02-26 5:14 ` Rusty Russell
2013-02-26 9:30 ` Michael S. Tsirkin
2013-02-26 7:02 ` Paolo Bonzini
2013-02-27 7:28 ` Rusty Russell
2013-02-27 7:49 ` Michael S. Tsirkin
2013-02-27 11:21 ` Rusty Russell
2013-02-28 9:24 ` Paolo Bonzini
2013-03-01 1:01 ` Rusty Russell
2013-02-19 7:56 ` [PATCH 03/16] virtio-blk: reorganize virtblk_add_req Rusty Russell
2013-02-19 7:56 ` [PATCH 04/16] virtio-blk: use virtqueue_start_buf on bio path Rusty Russell
2013-02-20 9:19 ` Asias He
2013-02-21 6:23 ` Rusty Russell
2013-02-19 7:56 ` [PATCH 05/16] virtio-blk: use virtqueue_add_sgs on req path Rusty Russell
2013-02-20 9:20 ` Asias He
2013-02-19 7:56 ` [PATCH 06/16] virtio_blk: remove nents member Rusty Russell
2013-02-20 9:20 ` Asias He
2013-02-19 7:56 ` [PATCH 07/16] virtio_ring: don't count elements twice for add_buf path Rusty Russell
2013-02-20 10:09 ` Wanlong Gao
2013-02-19 7:56 ` [PATCH 08/16] virtio_ring: virtqueue_add_outbuf / virtqueue_add_inbuf Rusty Russell
2013-02-20 10:09 ` Wanlong Gao
2013-02-21 17:09 ` Michael S. Tsirkin
2013-02-22 0:02 ` Rusty Russell
2013-02-25 21:35 ` Michael S. Tsirkin
2013-02-28 5:08 ` Rusty Russell
2013-02-28 7:01 ` Michael S. Tsirkin
2013-03-06 6:03 ` Rusty Russell [this message]
2013-02-19 7:56 ` [PATCH 09/16] virtio_net: use simplified virtqueue accessors Rusty Russell
2013-02-20 10:09 ` Wanlong Gao
2013-02-19 7:56 ` [PATCH 10/16] virtio_net: use virtqueue_add_sgs[] for command buffers Rusty Russell
2013-02-20 10:11 ` Wanlong Gao
2013-02-21 6:27 ` Rusty Russell
2013-02-21 8:30 ` Wanlong Gao
2013-02-21 9:41 ` Jason Wang
2013-02-21 9:43 ` Wanlong Gao
2013-02-19 7:56 ` [PATCH 11/16] virtio_rng: use simplified virtqueue accessors Rusty Russell
2013-02-20 10:12 ` Wanlong Gao
2013-02-19 7:56 ` [PATCH 12/16] virtio_console: " Rusty Russell
2013-02-20 10:12 ` Wanlong Gao
2013-02-19 7:56 ` [PATCH 13/16] caif_virtio: " Rusty Russell
2013-02-20 10:13 ` Wanlong Gao
2013-02-19 7:56 ` [PATCH 14/16] virtio_rpmsg_bus: " Rusty Russell
2013-02-20 10:14 ` Wanlong Gao
2013-02-19 7:56 ` [PATCH 15/16] virtio_balloon: " Rusty Russell
2013-02-20 10:15 ` Wanlong Gao
2013-02-19 7:56 ` [PATCH 16/16] 9p/trans_virtio.c: use virtio_add_sgs[] Rusty Russell
2013-02-19 9:15 ` [PATCH 00/16] virtio ring rework Paolo Bonzini
2013-02-21 6:30 ` Rusty Russell
2013-02-20 8:37 ` [PATCH 17/16] virtio-scsi: use virtqueue_add_sgs for command buffers Wanlong Gao
2013-02-20 9:38 ` Asias He
2013-02-20 9:41 ` Wanlong Gao
2013-02-20 9:47 ` [PATCH 17/16 V2] " Wanlong Gao
2013-02-20 10:54 ` Paolo Bonzini
2013-02-20 12:17 ` Asias He
2013-02-21 6:34 ` Rusty Russell
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