From: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
To: Chris Wilson <chris@chris-wilson.co.uk>, intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH v2 1/7] drm/i915/perf: rework aging tail workaround
Date: Tue, 19 Feb 2019 10:31:52 +0000 [thread overview]
Message-ID: <cf36df9a-5100-8e5f-6c43-4cc651f67bef@intel.com> (raw)
In-Reply-To: <155056789335.30979.1043669337133636373@skylake-alporthouse-com>
On 19/02/2019 09:18, Chris Wilson wrote:
> Quoting Lionel Landwerlin (2019-02-18 18:35:28)
>> We're about to introduce an options to open the perf stream, giving
>> the user ability to configure how often it wants the kernel to poll
>> the OA registers for available data.
>>
>> Right now the workaround against the OA tail pointer race condition
>> requires at least twice the internal kernel polling timer to make any
>> data available.
> I think this code is bogus. I do not think there is an aging problem on
> hsw+, the only cause of zeroes being written that I've found is from
> changing configs.
> -Chris
>
Hmm... I'm pretty sure there is an issue and it's actually worse on the
HSW machine I have than on later machines.
The DRM_NOTE in that function is appearing a lot more on HSW.
Yes, there is also an issue with how long it takes to reprogram the GPU.
-Lionel
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next prev parent reply other threads:[~2019-02-19 10:31 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-18 18:35 [PATCH v2 0/7] drm/i915/perf: add OA interrupt support Lionel Landwerlin
2019-02-18 18:35 ` [PATCH v2 1/7] drm/i915/perf: rework aging tail workaround Lionel Landwerlin
2019-02-19 9:18 ` Chris Wilson
2019-02-19 10:31 ` Lionel Landwerlin [this message]
2019-02-19 10:36 ` Chris Wilson
2019-02-19 10:56 ` Lionel Landwerlin
2019-02-18 18:35 ` [PATCH v2 2/7] drm/i915/perf: move pollin setup to non hw specific code Lionel Landwerlin
2019-02-18 18:35 ` [PATCH v2 3/7] drm/i915/perf: only append status when data is available Lionel Landwerlin
2019-02-18 18:35 ` [PATCH v2 4/7] drm/i915/perf: add new open param to configure polling of OA buffer Lionel Landwerlin
2019-02-18 18:35 ` [PATCH v2 5/7] drm/i915: handle interrupts from the OA unit Lionel Landwerlin
2019-02-18 18:35 ` [PATCH v2 6/7] drm/i915/perf: add interrupt enabling parameter Lionel Landwerlin
2019-02-18 18:35 ` [PATCH v2 7/7] drm/i915/perf: add flushing ioctl Lionel Landwerlin
2019-02-18 18:53 ` ✗ Fi.CI.CHECKPATCH: warning for drm/i915/perf: add OA interrupt support (rev3) Patchwork
2019-02-18 18:56 ` ✗ Fi.CI.SPARSE: " Patchwork
2019-02-18 19:15 ` ✓ Fi.CI.BAT: success " Patchwork
2019-02-18 23:34 ` ✓ Fi.CI.IGT: " Patchwork
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