From: "Goel, Akash" <akash.goel@intel.com>
To: "Chris Wilson" <chris@chris-wilson.co.uk>,
"Daniel Vetter" <daniel@ffwll.ch>,
intel-gfx@lists.freedesktop.org,
"Ville Syrjälä" <ville.syrjala@linux.intel.com>,
"Daniel Vetter" <daniel.vetter@ffwll.ch>,
"Jesse Barnes" <jbarnes@virtuousgeek.org>
Subject: Re: [PATCH] drm/i915: Only move to the CPU write domain if keeping the GTT pages
Date: Sun, 9 Aug 2015 17:11:52 +0530 [thread overview]
Message-ID: <55C73C80.8030106@intel.com> (raw)
In-Reply-To: <20150809105557.GA10889@nuc-i3427.alporthouse.com>
On 8/9/2015 4:25 PM, Chris Wilson wrote:
> On Sun, Aug 09, 2015 at 04:23:01PM +0530, Goel, Akash wrote:
>> On 8/7/2015 1:37 PM, Daniel Vetter wrote:
>>> I presume though you only want to avoid clflush when actually purging an
>>> object, so maybe we can keep this by purging the shmem backing node first
>>> and checking here for __I915_MADV_PURGED instead?
>>
>> An object marked as MADV_DONT_NEED, implies that it will be
>> purged/truncated right away after the call to put_pages_gtt
>> function.
>> So doing the other way round by purging first and then checking for
>> __I915_MADV_PURGED, might be equivalent.
>
> But disregards a few nice sanity checks, which I would like to keep.
> -Chris
Fine, just wanted to convey that doing the other way round may not be
really beneficial.
About the other point of virtually indexed/physically tagged cache,
would it be safe just rely on the MADV_DONT_NEED state of the object
(which indicates that there are no active CPU mmappings) ?
Due to an earlier CPU mmappings, there could be cachelines holding the
stale data ?
Best regards
Akash
>
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next prev parent reply other threads:[~2015-08-09 11:41 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-06 16:43 [PATCH] drm/i915: Only move to the CPU write domain if keeping the GTT pages Chris Wilson
2015-08-07 8:07 ` Daniel Vetter
2015-08-07 10:10 ` Chris Wilson
2015-08-07 11:55 ` Daniel Vetter
2015-08-07 13:07 ` Chris Wilson
2015-08-12 12:35 ` Daniel Vetter
2015-08-12 12:45 ` Chris Wilson
2015-08-09 10:53 ` Goel, Akash
2015-08-09 10:55 ` Chris Wilson
2015-08-09 11:41 ` Goel, Akash [this message]
2015-08-09 12:49 ` Chris Wilson
2015-08-09 13:32 ` Goel, Akash
2015-08-19 14:24 ` akash goel
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