From: Daniel Vetter <daniel@ffwll.ch>
To: Rob Clark <robdclark@gmail.com>
Cc: dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org,
"Daniel Vetter" <daniel@ffwll.ch>,
"Christian König" <ckoenig.leichtzumerken@gmail.com>,
"Michel Dänzer" <michel@daenzer.net>,
"Pekka Paalanen" <ppaalanen@gmail.com>,
"Rob Clark" <robdclark@chromium.org>,
"Christian König" <christian.koenig@amd.com>,
"Sumit Semwal" <sumit.semwal@linaro.org>,
"Gustavo Padovan" <gustavo@padovan.org>,
"open list:SYNC FILE FRAMEWORK" <linux-media@vger.kernel.org>,
"open list" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 1/9] dma-fence: Add deadline awareness
Date: Wed, 8 Sep 2021 19:55:59 +0200 [thread overview]
Message-ID: <YTj5LzD19u5Rgz+J@phenom.ffwll.local> (raw)
In-Reply-To: <20210903184806.1680887-2-robdclark@gmail.com>
On Fri, Sep 03, 2021 at 11:47:52AM -0700, Rob Clark wrote:
> From: Rob Clark <robdclark@chromium.org>
>
> Add a way to hint to the fence signaler of an upcoming deadline, such as
> vblank, which the fence waiter would prefer not to miss. This is to aid
> the fence signaler in making power management decisions, like boosting
> frequency as the deadline approaches and awareness of missing deadlines
> so that can be factored in to the frequency scaling.
>
> v2: Drop dma_fence::deadline and related logic to filter duplicate
> deadlines, to avoid increasing dma_fence size. The fence-context
> implementation will need similar logic to track deadlines of all
> the fences on the same timeline. [ckoenig]
>
> Signed-off-by: Rob Clark <robdclark@chromium.org>
> Reviewed-by: Christian König <christian.koenig@amd.com>
> Signed-off-by: Rob Clark <robdclark@chromium.org>
> ---
> drivers/dma-buf/dma-fence.c | 20 ++++++++++++++++++++
> include/linux/dma-fence.h | 16 ++++++++++++++++
> 2 files changed, 36 insertions(+)
>
> diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
> index ce0f5eff575d..1f444863b94d 100644
> --- a/drivers/dma-buf/dma-fence.c
> +++ b/drivers/dma-buf/dma-fence.c
> @@ -910,6 +910,26 @@ dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count,
> }
> EXPORT_SYMBOL(dma_fence_wait_any_timeout);
>
> +
> +/**
> + * dma_fence_set_deadline - set desired fence-wait deadline
> + * @fence: the fence that is to be waited on
> + * @deadline: the time by which the waiter hopes for the fence to be
> + * signaled
> + *
> + * Inform the fence signaler of an upcoming deadline, such as vblank, by
> + * which point the waiter would prefer the fence to be signaled by. This
> + * is intended to give feedback to the fence signaler to aid in power
> + * management decisions, such as boosting GPU frequency if a periodic
> + * vblank deadline is approaching.
> + */
> +void dma_fence_set_deadline(struct dma_fence *fence, ktime_t deadline)
> +{
> + if (fence->ops->set_deadline && !dma_fence_is_signaled(fence))
> + fence->ops->set_deadline(fence, deadline);
> +}
> +EXPORT_SYMBOL(dma_fence_set_deadline);
> +
> /**
> * dma_fence_init - Initialize a custom fence.
> * @fence: the fence to initialize
> diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
> index 6ffb4b2c6371..9c809f0d5d0a 100644
> --- a/include/linux/dma-fence.h
> +++ b/include/linux/dma-fence.h
> @@ -99,6 +99,7 @@ enum dma_fence_flag_bits {
> DMA_FENCE_FLAG_SIGNALED_BIT,
> DMA_FENCE_FLAG_TIMESTAMP_BIT,
> DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
> + DMA_FENCE_FLAG_HAS_DEADLINE_BIT,
> DMA_FENCE_FLAG_USER_BITS, /* must always be last member */
> };
>
> @@ -261,6 +262,19 @@ struct dma_fence_ops {
> */
> void (*timeline_value_str)(struct dma_fence *fence,
> char *str, int size);
> +
> + /**
> + * @set_deadline:
> + *
> + * Callback to allow a fence waiter to inform the fence signaler of an
> + * upcoming deadline, such as vblank, by which point the waiter would
> + * prefer the fence to be signaled by. This is intended to give feedback
> + * to the fence signaler to aid in power management decisions, such as
> + * boosting GPU frequency.
Please add here that this callback is called without &dma_fence.lock held,
and that locking is up to callers if they have some state to manage.
I realized that while scratching some heads over your later patches.
-Daniel
> + *
> + * This callback is optional.
> + */
> + void (*set_deadline)(struct dma_fence *fence, ktime_t deadline);
> };
>
> void dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
> @@ -586,6 +600,8 @@ static inline signed long dma_fence_wait(struct dma_fence *fence, bool intr)
> return ret < 0 ? ret : 0;
> }
>
> +void dma_fence_set_deadline(struct dma_fence *fence, ktime_t deadline);
> +
> struct dma_fence *dma_fence_get_stub(void);
> struct dma_fence *dma_fence_allocate_private_stub(void);
> u64 dma_fence_context_alloc(unsigned num);
> --
> 2.31.1
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
next prev parent reply other threads:[~2021-09-08 17:56 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-03 18:47 [PATCH v3 0/9] dma-fence: Deadline awareness Rob Clark
2021-09-03 18:47 ` [PATCH v3 1/9] dma-fence: Add deadline awareness Rob Clark
2021-09-08 17:55 ` Daniel Vetter [this message]
2021-09-03 18:47 ` [PATCH v3 2/9] drm/vblank: Add helper to get next vblank time Rob Clark
2021-09-03 18:47 ` [PATCH v3 3/9] drm/atomic-helper: Set fence deadline for vblank Rob Clark
2021-09-03 18:47 ` [PATCH v3 4/9] drm/scheduler: Add fence deadline support Rob Clark
2021-09-08 17:45 ` Daniel Vetter
2021-09-09 6:22 ` Christian König
2021-09-14 13:38 ` Daniel Vetter
2021-09-21 15:57 ` Rob Clark
2021-09-21 16:35 ` Rob Clark
2021-09-21 16:45 ` Christian König
2021-09-21 20:09 ` Andrey Grodzovsky
2021-09-21 20:47 ` Rob Clark
2021-09-22 2:18 ` Andrey Grodzovsky
2021-09-22 3:32 ` Rob Clark
2021-09-22 14:31 ` Andrey Grodzovsky
2021-09-22 15:01 ` Rob Clark
2021-09-03 18:47 ` [PATCH v3 5/9] drm/msm: Add deadline based boost support Rob Clark
2021-09-08 17:48 ` Daniel Vetter
2021-09-08 17:57 ` Rob Clark
2021-09-03 18:47 ` [PATCH v3 6/9] dma-buf/fence-array: Add fence deadline support Rob Clark
2021-09-08 18:00 ` Daniel Vetter
2021-09-09 6:55 ` Christian König
2021-09-03 18:47 ` [PATCH v3 7/9] dma-buf/fence-chain: " Rob Clark
2021-09-08 17:54 ` Daniel Vetter
2021-09-08 18:19 ` Rob Clark
2021-09-08 18:45 ` Daniel Vetter
2021-09-09 6:31 ` Christian König
2021-09-03 18:47 ` [PATCH v3 8/9] dma-buf/sync_file: Add SET_DEADLINE ioctl Rob Clark
2021-09-08 17:50 ` Daniel Vetter
2021-09-08 18:23 ` Rob Clark
2021-09-08 18:49 ` Daniel Vetter
2021-09-08 19:40 ` Rob Clark
2021-09-08 21:10 ` Daniel Vetter
2021-09-21 18:08 ` Rob Clark
2021-09-27 8:42 ` Pekka Paalanen
2021-09-27 8:53 ` Christian König
2021-09-27 14:36 ` Rob Clark
2021-09-28 7:57 ` Pekka Paalanen
2021-09-03 18:48 ` [PATCH v3 9/9] dma-buf/sw_sync: Add fence deadline support Rob Clark
2021-09-09 16:16 ` [PATCH v3 0/9] dma-fence: Deadline awareness Simon Ser
2021-09-09 16:35 ` Rob Clark
2021-09-09 16:42 ` Simon Ser
2021-09-09 17:08 ` Rob Clark
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