[Mesa-dev] [PATCH] i965: Disable compaction for EOT send messages

Ben Widawsky ben at bwidawsk.net
Thu May 28 18:12:52 PDT 2015

On Thu, May 28, 2015 at 04:58:23PM -0700, Matt Turner wrote:
> On Wed, May 27, 2015 at 10:16 PM, Ben Widawsky
> <benjamin.widawsky at intel.com> wrote:
> > AFAICT, there is no real way to make sure a send message with EOT is properly
> > ignored from compact, nor can I see a way to actually encode EOT while
> > compacting. Before the single send optimization we'd always bail because we hit
> > the is_immediate && !is_compactable_immediate case. However, with single send,
> > is_immediate is not true, and so we end up trying to compact the un-compactible.
> >
> > Without this, any compacting single send instruction will hang because the EOT
> > isn't there. I am not sure how I didn't hit this when I originally enabled the
> > optimization.  I didn't check if some surrounding code changed.
> >
> > NOTE: This needs another piglit run or two before merge.
> >
> > I know Neil and Matt were both looking into this. I did a quick search and
> > didn't see any patches out there to handle this. Please ignore if this has
> > already been sent by someone. (Direct me to it and I will review it).
> >
> > Cc: Matt Turner <mattst88 at gmail.com>
> > Cc: Neil Roberts <neil at linux.intel.com>
> > Cc: Mark Janes <mark.a.janes at intel.com>
> > Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
> I haven't figured out precisely how EOT's getting lost yet, but Mark
> says that with this patch we can actually complete a piglit run, so
> let's do it.
> Reviewed-by: Matt Turner <mattst88 at gmail.com>

Just a reminder... I gave you the quick explanation of what's going on in the
office an hour ago. Perhaps you can take a look and see if you can find a better
fix before I push. I am in no huge hurry.

Also, I should probably cc stable this for 10.6

Ben Widawsky, Intel Open Source Technology Center

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