From: Daniel Vetter <daniel@ffwll.ch>
To: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>,
dri-devel@lists.freedesktop.org,
Jason Ekstrand <jason.ekstrand@intel.com>,
Akash Goel <akash.goel@intel.com>,
stable@vger.kernel.org, intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 06/64] drm: Restore double clflush on the last partial cacheline
Date: Tue, 12 Jul 2016 15:57:44 +0200 [thread overview]
Message-ID: <20160712135744.GI23520@phenom.ffwll.local> (raw)
In-Reply-To: <1467880930-23082-6-git-send-email-chris@chris-wilson.co.uk>
On Thu, Jul 07, 2016 at 09:41:12AM +0100, Chris Wilson wrote:
> This effectively reverts
>
> commit afcd950cafea6e27b739fe7772cbbeed37d05b8b
> Author: Chris Wilson <chris@chris-wilson.co.uk>
> Date: Wed Jun 10 15:58:01 2015 +0100
>
> drm: Avoid the double clflush on the last cache line in drm_clflush_virt_range()
>
> as we have observed issues with serialisation of the clflush operations
> on Baytrail+ Atoms with partial updates. Applying the double flush on the
> last cacheline forces that clflush to be ordered with respect to the
> previous clflush, and the mfence then protects against prefetches crossing
> the clflush boundary.
>
> The same issue can be demonstrated in userspace with igt/gem_exec_flush.
>
> Fixes: afcd950cafea6 (drm: Avoid the double clflush on the last cache...)
> Testcase: igt/gem_concurrent_blit
> Testcase: igt/gem_partial_pread_pwrite
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92845
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: dri-devel@lists.freedesktop.org
> Cc: Akash Goel <akash.goel@intel.com>
> Cc: Imre Deak <imre.deak@intel.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Jason Ekstrand <jason.ekstrand@intel.com>
> Cc: stable@vger.kernel.org
> Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
It's duct-tape, but oh well. Applied to drm-misc.
-Daniel
> ---
> drivers/gpu/drm/drm_cache.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/drm/drm_cache.c b/drivers/gpu/drm/drm_cache.c
> index 059f7c39c582..a7916e5f8864 100644
> --- a/drivers/gpu/drm/drm_cache.c
> +++ b/drivers/gpu/drm/drm_cache.c
> @@ -136,6 +136,7 @@ drm_clflush_virt_range(void *addr, unsigned long length)
> mb();
> for (; addr < end; addr += size)
> clflushopt(addr);
> + clflushopt(end - 1); /* force serialisation */
> mb();
> return;
> }
> --
> 2.8.1
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
next prev parent reply other threads:[~2016-07-12 13:57 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1467880930-23082-1-git-send-email-chris@chris-wilson.co.uk>
2016-07-07 8:41 ` [PATCH 06/64] drm: Restore double clflush on the last partial cacheline Chris Wilson
2016-07-12 13:57 ` Daniel Vetter [this message]
2016-07-13 8:07 ` Mika Kuoppala
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160712135744.GI23520@phenom.ffwll.local \
--to=daniel@ffwll.ch \
--cc=akash.goel@intel.com \
--cc=chris@chris-wilson.co.uk \
--cc=daniel.vetter@ffwll.ch \
--cc=dri-devel@lists.freedesktop.org \
--cc=intel-gfx@lists.freedesktop.org \
--cc=jason.ekstrand@intel.com \
--cc=stable@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox