From: "Keith Packard" <keithp@keithp.com>
To: Jason Ekstrand <jason@jlekstrand.net>
Cc: ML mesa-dev <mesa-dev@lists.freedesktop.org>,
Maling list - DRI developers <dri-devel@lists.freedesktop.org>
Subject: Re: [PATCH] vulkan: Add VK_EXT_calibrated_timestamps extension (radv and anv) [v4]
Date: Tue, 16 Oct 2018 14:51:41 -0700 [thread overview]
Message-ID: <87woqh7e6q.fsf@keithp.com> (raw)
In-Reply-To: <CAOFGe94mZT3naH=vzKvCG1EwRDLpdXez5nhg9i3Fc1gB5v+QoQ@mail.gmail.com>
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Jason Ekstrand <jason@jlekstrand.net> writes:
> You've got me almost convinced as well. Thanks for the diagrams! I think
> instead of adding 1 perhaps what we want is
>
> max2(sample_interval_ns, gpu_tick_ns + monotonic_tick_ns)
>
> Where monotonic_tick_ns is maybe as low as 1. Am I following you correctly?
Not quite; I was thinking that because the sample_interval_ns is
measured by sampling the monotonic clock twice, the actual interval can
be up to 1 tick longer, so
max2(sample_interval_ns + monotonic_tick_ns, gpu_tick_ns)
The gpu_tick_ns is computed, not measured, and so accurately reflects
the maximum deviation in the measurements.
--
-keith
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next prev parent reply other threads:[~2018-10-16 21:51 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-15 21:22 [PATCH] vulkan: Add VK_EXT_calibrated_timestamps extension (radv and anv) [v2] Keith Packard
2018-10-15 21:36 ` Jason Ekstrand
2018-10-15 21:38 ` Lionel Landwerlin
2018-10-15 23:05 ` [PATCH] vulkan: Add VK_EXT_calibrated_timestamps extension (radv and anv) [v3] Keith Packard
2018-10-16 1:06 ` Jason Ekstrand
2018-10-16 5:31 ` [Mesa-dev] " Keith Packard
2018-10-16 5:31 ` [PATCH] vulkan: Add VK_EXT_calibrated_timestamps extension (radv and anv) [v4] Keith Packard
2018-10-16 7:32 ` Samuel Pitoiset
2018-10-16 7:33 ` Bas Nieuwenhuizen
2018-10-16 19:34 ` Keith Packard
2018-10-16 19:44 ` Jason Ekstrand
2018-10-16 21:07 ` Keith Packard
2018-10-16 21:33 ` Jason Ekstrand
2018-10-16 21:51 ` Keith Packard [this message]
2018-10-16 21:38 ` Bas Nieuwenhuizen
2018-10-16 22:06 ` Keith Packard
2018-10-16 22:28 ` Bas Nieuwenhuizen
2018-10-16 22:56 ` Keith Packard
2018-10-17 2:18 ` Jason Ekstrand
2018-10-17 5:14 ` Keith Packard
2018-10-17 15:34 ` Jason Ekstrand
2018-10-17 1:55 ` Jason Ekstrand
2018-10-17 5:01 ` Keith Packard
2018-10-17 16:49 ` [PATCH] vulkan: Add VK_EXT_calibrated_timestamps extension (radv and anv) [v5] Keith Packard
2018-10-17 17:06 ` Jason Ekstrand
2018-10-17 17:24 ` [Mesa-dev] " Keith Packard
2018-10-17 22:49 ` Bas Nieuwenhuizen
2018-10-18 3:14 ` Keith Packard
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