From: Daniel Vetter <daniel@ffwll.ch>
To: "Christian König" <ckoenig.leichtzumerken@gmail.com>
Cc: 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: Re: Use dma_fence_array for implementing shared dma_resv fences
Date: Tue, 27 Aug 2019 18:37:41 +0200 [thread overview]
Message-ID: <20190827163741.GD2112@phenom.ffwll.local> (raw)
In-Reply-To: <20190826145731.1725-1-christian.koenig@amd.com>
On Mon, Aug 26, 2019 at 04:57:22PM +0200, Christian König wrote:
> 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.
I think more specific point for publishing fences makes a lot of sense, so
this sounds like a solid improvement on the dma_resv api. I'm working on
some dma_fence instrumentation where that at least might be useful.
/me back to burried state
Cheers, Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
prev parent reply other threads:[~2019-08-27 16:37 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
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
2019-08-27 11:44 ` Chris Wilson
2019-08-26 14:57 ` [PATCH 2/9] dma-buf: make to_dma_fence_array NULL safe Christian König
2019-08-30 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 ` [PATCH 4/9] dma-buf: add dma_fence_array_recycle v2 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 ` [PATCH 6/9] dma-buf/resv: add dma_resv_prune_fences v2 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 ` [PATCH 8/9] dma-buf/resv: use new dma_fence_array based implementation Christian König
2019-08-26 14:57 ` [PATCH 9/9] dma-buf/resv: drop the sequence count Christian König
2019-08-27 16:37 ` Daniel Vetter [this message]
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