[PATCH] [WIP] i965: Use up to 80 WM threads on GT2.

[PATCH] [WIP] i965: Use up to 80 WM threads on GT2.

[Eric Anholt]

---

Here's an idea for an SNB performance improvement from the specs.  It
says that on GT2 you should be able to use 80 threads if "WIZ Hashing
Disable in GT_MODE register enabled".  On my system (supposedly GT2),
that bit (bit 6 of 0x20d0) is unset.  In testing, with intel_reg_write
0x20d0 0x00400040 (it only successfully took once, I suspect due to
FORCEWAKE, which also means that I can't necessarily trust that the
bit was unset originally), I got only hangs from 3D.


 src/mesa/drivers/dri/i965/brw_context.c    |    6 +++++-
 src/mesa/drivers/dri/i965/gen6_wm_state.c  |    2 +-
 src/mesa/drivers/dri/intel/intel_chipset.h |   10 ++++++----
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
index 9483ec6..3555e44 100644
--- a/src/mesa/drivers/dri/i965/brw_context.c
+++ b/src/mesa/drivers/dri/i965/brw_context.c
@@ -184,7 +184,11 @@ GLboolean brwCreateContext( int api,
    if (intel->gen >= 6) {
       brw->urb.size = 1024;
       brw->vs_max_threads = 60;
-      brw->wm_max_threads = 80;
+      if (IS_GT2(intel->intelScreen->deviceID)) {
+	 brw->wm_max_threads = 80;
+      } else {
+	 brw->wm_max_threads = 40;
+      }
    } else if (intel->gen == 5) {
       brw->urb.size = 1024;
       brw->vs_max_threads = 72;
diff --git a/src/mesa/drivers/dri/i965/gen6_wm_state.c b/src/mesa/drivers/dri/i965/gen6_wm_state.c
index 78901ec..b91e1c1 100644
--- a/src/mesa/drivers/dri/i965/gen6_wm_state.c
+++ b/src/mesa/drivers/dri/i965/gen6_wm_state.c
@@ -144,7 +144,7 @@ upload_wm_state(struct brw_context *brw)
    dw4 |= (brw->wm.prog_data->first_curbe_grf <<
 	   GEN6_WM_DISPATCH_START_GRF_SHIFT_0);
 
-   dw5 |= (40 - 1) << GEN6_WM_MAX_THREADS_SHIFT;
+   dw5 |= (brw->wm.max_threads - 1) << GEN6_WM_MAX_THREADS_SHIFT;
 
    /* CACHE_NEW_WM_PROG */
    if (brw->wm.prog_data->dispatch_width == 8)
diff --git a/src/mesa/drivers/dri/intel/intel_chipset.h b/src/mesa/drivers/dri/intel/intel_chipset.h
index 4ff9140..f7dcf47 100644
--- a/src/mesa/drivers/dri/intel/intel_chipset.h
+++ b/src/mesa/drivers/dri/intel/intel_chipset.h
@@ -125,12 +125,14 @@
 /* Compat macro for intel_decode.c */
 #define IS_IRONLAKE(devid)	IS_GEN5(devid)
 
-#define IS_GEN6(devid)		(devid == PCI_CHIP_SANDYBRIDGE_GT1 || \
-				 devid == PCI_CHIP_SANDYBRIDGE_GT2 || \
+#define IS_GT2(devid)		(devid == PCI_CHIP_SANDYBRIDGE_GT2 || \
 				 devid == PCI_CHIP_SANDYBRIDGE_GT2_PLUS	|| \
-				 devid == PCI_CHIP_SANDYBRIDGE_M_GT1 || \
 				 devid == PCI_CHIP_SANDYBRIDGE_M_GT2 || \
-				 devid == PCI_CHIP_SANDYBRIDGE_M_GT2_PLUS || \
+				 devid == PCI_CHIP_SANDYBRIDGE_M_GT2_PLUS)
+
+#define IS_GEN6(devid)		(IS_GT2(devid) || \
+				 devid == PCI_CHIP_SANDYBRIDGE_GT1 || \
+				 devid == PCI_CHIP_SANDYBRIDGE_M_GT1 || \
 				 devid == PCI_CHIP_SANDYBRIDGE_S)
 
 #define IS_GT1(devid)		(devid == PCI_CHIP_SANDYBRIDGE_GT1 || \
-- 
1.7.4.1

Re: [PATCH] [WIP] i965: Use up to 80 WM threads on GT2.

[Ian Romanick]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 03/28/2011 10:55 AM, Eric Anholt wrote:

> Here's an idea for an SNB performance improvement from the specs.  It
> says that on GT2 you should be able to use 80 threads if "WIZ Hashing
> Disable in GT_MODE register enabled".  On my system (supposedly GT2),
> that bit (bit 6 of 0x20d0) is unset.  In testing, with intel_reg_write
> 0x20d0 0x00400040 (it only successfully took once, I suspect due to
> FORCEWAKE, which also means that I can't necessarily trust that the
> bit was unset originally), I got only hangs from 3D.

So, we're currently using too many threads in some cases?  Could this be
related to bug #35730?  In that case the failure seems to be limited to
SugarBay.  I believe that's GT1, but I can never get the code names for
these chips straight.
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Re: [PATCH] [WIP] i965: Use up to 80 WM threads on GT2.

[Ben Widawsky]

On Mon, Mar 28, 2011 at 10:55:40AM -0700, Eric Anholt wrote:
> ---
> I suspect due to
> FORCEWAKE, which also means that I can't necessarily trust that the
> bit was unset originally), I got only hangs from 3D.

If you want to get some more possibly garbage data, you can set
forcewake from userspace, and hope the kernel doesn't unset it :).

intel_reg_write 0xa18c 1
# check for ack
intel_reg_read 0x130090

I've never tried it, but it might work at least for reading that first
bit. I'm currenty working around this with <1301105269-23970-1-git-send-email-ben@bwidawsk.net>
and a hack in the kernel to do a get() and never do a put.

Ben

Re: [PATCH] [WIP] i965: Use up to 80 WM threads on GT2.

[Shuang He]

On 2011/3/29 6:22, Ian Romanick wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> On 03/28/2011 10:55 AM, Eric Anholt wrote:
>
>> Here's an idea for an SNB performance improvement from the specs.  It
>> says that on GT2 you should be able to use 80 threads if "WIZ Hashing
>> Disable in GT_MODE register enabled".  On my system (supposedly GT2),
>> that bit (bit 6 of 0x20d0) is unset.  In testing, with intel_reg_write
>> 0x20d0 0x00400040 (it only successfully took once, I suspect due to
>> FORCEWAKE, which also means that I can't necessarily trust that the
>> bit was unset originally), I got only hangs from 3D.
> So, we're currently using too many threads in some cases?  Could this be
> related to bug #35730?  In that case the failure seems to be limited to
> SugarBay.  I believe that's GT1, but I can never get the code names for
> these chips straight.

The system environment description section in bug #35730 already mention 
it's rev09 GT1

Thanks
     --Shuang

> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.4.11 (GNU/Linux)
> Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org/
>
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> oD4An2DMFJdXfYKOyvehR7x6qAQnYix6
> =4m/t
> -----END PGP SIGNATURE-----
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Re: [PATCH] [WIP] i965: Use up to 80 WM threads on GT2.

[Eric Anholt]

[-- Attachment #1.1: Type: text/plain, Size: 1078 bytes --]

On Mon, 28 Mar 2011 15:22:35 -0700, Ian Romanick <idr@freedesktop.org> wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> On 03/28/2011 10:55 AM, Eric Anholt wrote:
> 
> > Here's an idea for an SNB performance improvement from the specs.  It
> > says that on GT2 you should be able to use 80 threads if "WIZ Hashing
> > Disable in GT_MODE register enabled".  On my system (supposedly GT2),
> > that bit (bit 6 of 0x20d0) is unset.  In testing, with intel_reg_write
> > 0x20d0 0x00400040 (it only successfully took once, I suspect due to
> > FORCEWAKE, which also means that I can't necessarily trust that the
> > bit was unset originally), I got only hangs from 3D.
> 
> So, we're currently using too many threads in some cases?  Could this be
> related to bug #35730?  In that case the failure seems to be limited to
> SugarBay.  I believe that's GT1, but I can never get the code names for
> these chips straight.

Nope, note how instead of using that original wm_max_threads value, 40
is hardcoded in the place that should have been using it.

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Re: [PATCH] [WIP] i965: Use up to 80 WM threads on GT2.

[Eric Anholt]

[-- Attachment #1.1: Type: text/plain, Size: 1010 bytes --]

On Mon, 28 Mar 2011 15:37:37 -0700, Ben Widawsky <ben@bwidawsk.net> wrote:
> On Mon, Mar 28, 2011 at 10:55:40AM -0700, Eric Anholt wrote:
> > ---
> > I suspect due to
> > FORCEWAKE, which also means that I can't necessarily trust that the
> > bit was unset originally), I got only hangs from 3D.
> 
> If you want to get some more possibly garbage data, you can set
> forcewake from userspace, and hope the kernel doesn't unset it :).
> 
> intel_reg_write 0xa18c 1
> # check for ack
> intel_reg_read 0x130090
> 
> I've never tried it, but it might work at least for reading that first
> bit. I'm currenty working around this with <1301105269-23970-1-git-send-email-ben@bwidawsk.net>
> and a hack in the kernel to do a get() and never do a put.

I'm tempted by the idea of having a kernel interface for unpriveleged
interfaces for reading these regs, which would allow for non-root
gpu_top in addition to doing the forcewake.  It'll suck to maintain a
list of unpriveleged-OK regs, though.

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Re: [PATCH] [WIP] i965: Use up to 80 WM threads on GT2.

[Chris Wilson]

On Mon, 28 Mar 2011 21:43:28 -0700, Eric Anholt <eric@anholt.net> wrote:
> On Mon, 28 Mar 2011 15:22:35 -0700, Ian Romanick <idr@freedesktop.org> wrote:
> > So, we're currently using too many threads in some cases?  Could this be
> > related to bug #35730?  In that case the failure seems to be limited to
> > SugarBay.  I believe that's GT1, but I can never get the code names for
> > these chips straight.
> 
> Nope, note how instead of using that original wm_max_threads value, 40
> is hardcoded in the place that should have been using it.

But for DevSmallGT (which *is* GT1 right?) max VS threads is only 24.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre