From: Eric Anholt <eric@anholt.net>
To: Chris Wilson <chris@chris-wilson.co.uk>, igt-dev@lists.freedesktop.org
Subject: Re: [igt-dev] [PATCH igt] lib: Provide an accelerated routine for readback from WC
Date: Tue, 27 Feb 2018 15:29:04 -0800 [thread overview]
Message-ID: <87muzut3jz.fsf@anholt.net> (raw)
In-Reply-To: <20180227215040.11297-1-chris@chris-wilson.co.uk>
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Chris Wilson <chris@chris-wilson.co.uk> writes:
> Reading from WC is awfully slow as each access is uncached and so
> performed synchronously, stalling for the memory load. x86 did introduce
> some new instructions in SSE 4.1 to provide a small internal buffer to
> accelerate reading back a cacheline at a time from uncached memory, for
> this purpose.
I think without a _mm_mfence() before the movntdqas, you can get stale
results from movntdqa's little cache.
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next prev parent reply other threads:[~2018-02-27 23:29 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-27 21:50 [igt-dev] [PATCH igt] lib: Provide an accelerated routine for readback from WC Chris Wilson
2018-02-27 21:53 ` Chris Wilson
2018-02-27 22:17 ` [igt-dev] [PATCH igt v2] " Chris Wilson
2018-02-27 22:20 ` [igt-dev] [PATCH igt v3] " Chris Wilson
2018-02-27 22:42 ` [igt-dev] [PATCH igt v4] " Chris Wilson
2018-02-27 23:29 ` Eric Anholt [this message]
2018-02-27 23:44 ` [igt-dev] ✓ Fi.CI.BAT: success for lib: Provide an accelerated routine for readback from WC (rev4) Patchwork
2018-02-28 1:04 ` [igt-dev] ✗ Fi.CI.IGT: failure " Patchwork
2018-02-28 9:00 ` [igt-dev] [PATCH igt v6] lib: Provide an accelerated routine for readback from WC Chris Wilson
2018-02-28 17:12 ` Ville Syrjälä
2018-03-01 8:43 ` Chris Wilson
2018-02-28 9:31 ` [igt-dev] ✓ Fi.CI.BAT: success for lib: Provide an accelerated routine for readback from WC (rev5) Patchwork
2018-02-28 10:16 ` [igt-dev] ✓ Fi.CI.IGT: " Patchwork
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