From: Chris Wilson <chris@chris-wilson.co.uk> To: dri-devel@lists.freedesktop.org Cc: intel-gfx@lists.freedesktop.org, Chris Wilson <chris@chris-wilson.co.uk>, Sumit Semwal <sumit.semwal@linaro.org>, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org Subject: [PATCH 11/11] dma-buf: Do a fast lockless check for poll with timeout=0 Date: Mon, 29 Aug 2016 08:08:34 +0100 [thread overview] Message-ID: <20160829070834.22296-11-chris@chris-wilson.co.uk> (raw) In-Reply-To: <20160829070834.22296-1-chris@chris-wilson.co.uk> Currently we install a callback for performing poll on a dma-buf, irrespective of the timeout. This involves taking a spinlock, as well as unnecessary work, and greatly reduces scaling of poll(.timeout=0) across multiple threads. We can query whether the poll will block prior to installing the callback to make the busy-query fast. Single thread: 60% faster 8 threads on 4 (+4 HT) cores: 600% faster Still not quite the perfect scaling we get with a native busy ioctl, but poll(dmabuf) is faster due to the quicker lookup of the object and avoiding drm_ioctl(). Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> --- drivers/dma-buf/dma-buf.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index cf04d249a6a4..c7a7bc579941 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -156,6 +156,18 @@ static unsigned int dma_buf_poll(struct file *file, poll_table *poll) if (!events) return 0; + if (poll_does_not_wait(poll)) { + if (events & POLLOUT && + !reservation_object_test_signaled_rcu(resv, true)) + events &= ~(POLLOUT | POLLIN); + + if (events & POLLIN && + !reservation_object_test_signaled_rcu(resv, false)) + events &= ~POLLIN; + + return events; + } + retry: seq = read_seqcount_begin(&resv->seq); rcu_read_lock(); -- 2.9.3
WARNING: multiple messages have this Message-ID (diff)
From: Chris Wilson <chris@chris-wilson.co.uk> To: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org, intel-gfx@lists.freedesktop.org, linux-media@vger.kernel.org Subject: [PATCH 11/11] dma-buf: Do a fast lockless check for poll with timeout=0 Date: Mon, 29 Aug 2016 08:08:34 +0100 [thread overview] Message-ID: <20160829070834.22296-11-chris@chris-wilson.co.uk> (raw) In-Reply-To: <20160829070834.22296-1-chris@chris-wilson.co.uk> Currently we install a callback for performing poll on a dma-buf, irrespective of the timeout. This involves taking a spinlock, as well as unnecessary work, and greatly reduces scaling of poll(.timeout=0) across multiple threads. We can query whether the poll will block prior to installing the callback to make the busy-query fast. Single thread: 60% faster 8 threads on 4 (+4 HT) cores: 600% faster Still not quite the perfect scaling we get with a native busy ioctl, but poll(dmabuf) is faster due to the quicker lookup of the object and avoiding drm_ioctl(). Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> --- drivers/dma-buf/dma-buf.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index cf04d249a6a4..c7a7bc579941 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -156,6 +156,18 @@ static unsigned int dma_buf_poll(struct file *file, poll_table *poll) if (!events) return 0; + if (poll_does_not_wait(poll)) { + if (events & POLLOUT && + !reservation_object_test_signaled_rcu(resv, true)) + events &= ~(POLLOUT | POLLIN); + + if (events & POLLIN && + !reservation_object_test_signaled_rcu(resv, false)) + events &= ~POLLIN; + + return events; + } + retry: seq = read_seqcount_begin(&resv->seq); rcu_read_lock(); -- 2.9.3 _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2016-08-29 7:25 UTC|newest] Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-08-29 7:08 [PATCH 01/11] drm/amdgpu: Remove call to reservation_object_test_signaled_rcu before wait Chris Wilson 2016-08-29 7:08 ` [PATCH 02/11] drm/etnaviv: Remove manual " Chris Wilson 2016-09-23 12:55 ` Daniel Vetter 2016-10-05 16:15 ` Sumit Semwal 2016-10-10 13:17 ` Lucas Stach 2016-08-29 7:08 ` [PATCH 03/11] drm/msm: Remove " Chris Wilson 2016-09-23 12:55 ` Daniel Vetter 2016-09-23 13:07 ` [Intel-gfx] " Rob Clark 2016-08-29 7:08 ` [PATCH 04/11] drm/nouveau: " Chris Wilson 2016-09-23 12:55 ` Daniel Vetter 2016-10-05 16:05 ` Sumit Semwal 2016-08-29 7:08 ` [PATCH 05/11] drm/vmwgfx: " Chris Wilson 2016-09-23 12:56 ` Daniel Vetter 2016-10-05 16:11 ` [Intel-gfx] " Sumit Semwal 2016-10-05 17:03 ` Sinclair Yeh 2016-08-29 7:08 ` [PATCH 06/11] dma-buf: Introduce fence_get_rcu_safe() Chris Wilson 2016-08-29 7:08 ` Chris Wilson 2016-09-23 12:59 ` Daniel Vetter 2016-09-23 12:59 ` Daniel Vetter 2016-09-23 13:34 ` Markus Heiser 2016-09-23 13:34 ` Markus Heiser 2016-08-29 7:08 ` [PATCH 07/11] dma-buf: Restart reservation_object_get_fences_rcu() after writes Chris Wilson 2016-08-29 7:08 ` Chris Wilson 2016-09-23 13:03 ` Daniel Vetter 2016-09-23 13:03 ` Daniel Vetter 2016-08-29 7:08 ` [PATCH 08/11] dma-buf: Restart reservation_object_wait_timeout_rcu() " Chris Wilson 2016-08-29 7:08 ` Chris Wilson 2016-09-23 13:18 ` Daniel Vetter 2016-08-29 7:08 ` [PATCH 09/11] dma-buf: Restart reservation_object_test_signaled_rcu() " Chris Wilson 2016-08-29 7:08 ` Chris Wilson 2016-09-23 13:43 ` Daniel Vetter 2016-09-23 13:43 ` Daniel Vetter 2016-08-29 7:08 ` [PATCH 10/11] dma-buf: Use seqlock to close RCU race in test_signaled_single Chris Wilson 2016-08-29 7:08 ` Chris Wilson 2016-09-23 13:49 ` [Linaro-mm-sig] " Daniel Vetter 2016-09-23 13:49 ` Daniel Vetter 2016-09-23 14:02 ` Chris Wilson 2016-09-25 20:43 ` Daniel Vetter 2016-09-25 20:43 ` Daniel Vetter 2016-08-29 7:08 ` Chris Wilson [this message] 2016-08-29 7:08 ` [PATCH 11/11] dma-buf: Do a fast lockless check for poll with timeout=0 Chris Wilson 2016-08-29 18:16 ` [PATCH] dma-buf/sync-file: Avoid enable fence signaling if poll(.timeout=0) Chris Wilson 2016-08-29 18:16 ` Chris Wilson 2016-08-29 18:26 ` Gustavo Padovan 2016-09-13 14:46 ` Sumit Semwal 2016-09-13 14:46 ` Sumit Semwal 2016-09-15 0:00 ` Rafael Antognolli 2016-09-21 7:26 ` Gustavo Padovan 2016-09-21 11:08 ` Chris Wilson 2016-09-23 13:50 ` [Intel-gfx] [PATCH 11/11] dma-buf: Do a fast lockless check for poll with timeout=0 Daniel Vetter 2016-09-23 13:50 ` Daniel Vetter 2016-09-23 14:15 ` Chris Wilson 2016-09-23 15:06 ` Chris Wilson 2016-09-23 15:06 ` Chris Wilson 2016-09-23 15:20 ` [Intel-gfx] " Chris Wilson 2016-09-23 17:59 ` Christian König 2016-09-23 17:59 ` Christian König 2016-09-25 20:44 ` Daniel Vetter 2016-09-25 20:44 ` Daniel Vetter 2016-08-29 7:50 ` ✗ Fi.CI.BAT: warning for series starting with [01/11] drm/amdgpu: Remove call to reservation_object_test_signaled_rcu before wait Patchwork 2016-08-29 8:20 ` [PATCH 01/11] " Christian König 2016-09-23 12:54 ` Daniel Vetter 2016-10-05 16:03 ` Sumit Semwal
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