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From: "Christian König" <ckoenig.leichtzumerken@gmail.com>
To: dri-devel@lists.freedesktop.org, chris@chris-wilson.co.uk,
	daniel.vetter@ffwll.ch, sumit.semwal@linaro.org,
	linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org
Subject: Use dma_fence_array for implementing shared dma_resv fences
Date: Mon, 26 Aug 2019 16:57:22 +0200	[thread overview]
Message-ID: <20190826145731.1725-1-christian.koenig@amd.com> (raw)

This is the new dma_fence_array based container for shared fences in the dma_resv object.

Advantage of this approach is that you can grab a reference to the current set of shared fences at any time, which allows us to drop the sequence number increment and makes the whole RCU handling much more easier.

Disadvantage is that RCU users now have to grab a reference instead of using the sequence counter. As far as I can see i915 was actually the only driver doing this.

So we optimize for adding more fences instead of reading them now.

Another behavior change worth noting is that the shared fences are now only visible after unlocking the dma_resv object or calling dma_resv_fences_commit() manually.

Please review and/or comment,
Christian.



WARNING: multiple messages have this Message-ID (diff)
From: "Christian König" <ckoenig.leichtzumerken@gmail.com>
To: dri-devel@lists.freedesktop.org, chris@chris-wilson.co.uk,
	daniel.vetter@ffwll.ch, sumit.semwal@linaro.org,
	linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org
Subject: Use dma_fence_array for implementing shared dma_resv fences
Date: Mon, 26 Aug 2019 16:57:22 +0200	[thread overview]
Message-ID: <20190826145731.1725-1-christian.koenig@amd.com> (raw)

This is the new dma_fence_array based container for shared fences in the dma_resv object.

Advantage of this approach is that you can grab a reference to the current set of shared fences at any time, which allows us to drop the sequence number increment and makes the whole RCU handling much more easier.

Disadvantage is that RCU users now have to grab a reference instead of using the sequence counter. As far as I can see i915 was actually the only driver doing this.

So we optimize for adding more fences instead of reading them now.

Another behavior change worth noting is that the shared fences are now only visible after unlocking the dma_resv object or calling dma_resv_fences_commit() manually.

Please review and/or comment,
Christian.


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             reply	other threads:[~2019-08-26 14:57 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-26 14:57 Christian König [this message]
2019-08-26 14:57 ` Use dma_fence_array for implementing shared dma_resv fences Christian König
2019-08-26 14:57 ` [PATCH 1/9] dma-buf: fix dma_fence_array_signaled Christian König
2019-08-26 14:57   ` Christian König
2019-08-27 11:44   ` Chris Wilson
2019-08-27 11:44     ` Chris Wilson
2019-08-26 14:57 ` [PATCH 2/9] dma-buf: make to_dma_fence_array NULL safe Christian König
2019-08-26 14:57   ` Christian König
2019-08-30 16:07   ` Ruhl, Michael J
2019-08-30 16:07     ` Ruhl, Michael J
2019-08-26 14:57 ` [PATCH 3/9] dma-buf: add dma_fence_array_alloc/free Christian König
2019-08-26 14:57   ` Christian König
2019-08-26 14:57 ` [PATCH 4/9] dma-buf: add dma_fence_array_recycle v2 Christian König
2019-08-26 14:57   ` Christian König
2019-08-26 14:57 ` [PATCH 5/9] dma-buf: add dma_fence_array_for_each Christian König
2019-08-26 14:57   ` Christian König
2019-08-26 14:57 ` [PATCH 6/9] dma-buf/resv: add dma_resv_prune_fences v2 Christian König
2019-08-26 14:57   ` Christian König
2019-08-26 14:57 ` [PATCH 7/9] dma-buf/resv: add new fences container implementation Christian König
2019-08-26 14:57   ` Christian König
2019-08-26 14:57 ` [PATCH 8/9] dma-buf/resv: use new dma_fence_array based implementation Christian König
2019-08-26 14:57   ` Christian König
2019-08-26 14:57 ` [PATCH 9/9] dma-buf/resv: drop the sequence count Christian König
2019-08-26 14:57   ` Christian König
2019-08-27 16:37 ` Use dma_fence_array for implementing shared dma_resv fences Daniel Vetter
2019-08-27 16:37   ` Daniel Vetter

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