From: Chris Wilson <chris@chris-wilson.co.uk>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 1/2] drm/i915: Don't allow ring tail to reach the same cacheline as head
Date: Mon, 26 Nov 2012 20:24:10 +0000 [thread overview]
Message-ID: <eeac1e$54p8lc@AZSMGA002.ch.intel.com> (raw)
In-Reply-To: <20121126180200.GA21547@intel.com>
[-- Attachment #1: Type: text/plain, Size: 1107 bytes --]
On Mon, 26 Nov 2012 20:02:00 +0200, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> On Mon, Nov 26, 2012 at 04:28:33PM +0000, Chris Wilson wrote:
> > On Mon, 26 Nov 2012 14:48:18 +0200, ville.syrjala@linux.intel.com wrote:
> > > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > >
> > > According to BSpec the ring head and tail pointers must not be
> > > on the same cacheline when head > tail. The easiest way to enforce
> > > this is to reduce the reported ring space.
> >
> > I'm going to admit blindness because I don't see that warning in the
> > gen2-gen7 bspecs. Can you please give chapter and verse, and check to
> > see if there is a rationale?
>
> It's always the last thing in the section titled 'Ring Buffer Use'. I
> believe it's present in all the pre-snb internal bspecs, and it's also
> in all the public docs. I can't find it in the internal snb+ bspec but
> then again those don't seem to include the relevant chapter at all.
Gotcha. Yes, nice catch.
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
[-- Attachment #2: Type: text/plain, Size: 159 bytes --]
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/intel-gfx
next prev parent reply other threads:[~2012-11-26 20:24 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-26 12:48 [PATCH 0/2] drm/i915: Ring buffer stuff ville.syrjala
2012-11-26 12:48 ` [PATCH 1/2] drm/i915: Don't allow ring tail to reach the same cacheline as head ville.syrjala
2012-11-26 16:28 ` Chris Wilson
2012-11-26 18:02 ` Ville Syrjälä
2012-11-26 20:24 ` Chris Wilson [this message]
2012-11-26 12:48 ` [PATCH 2/2] drm/i915: Warn if ring tail is not qword aligned ville.syrjala
2012-11-26 15:55 ` Daniel Vetter
2012-11-26 16:25 ` Chris Wilson
2012-11-26 17:40 ` Ville Syrjälä
2012-11-26 17:46 ` Chris Wilson
2012-11-26 18:09 ` Ville Syrjälä
2012-11-27 6:04 ` Ben Widawsky
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='eeac1e$54p8lc@AZSMGA002.ch.intel.com' \
--to=chris@chris-wilson.co.uk \
--cc=intel-gfx@lists.freedesktop.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