| Message ID | 1423012791-5387-1-git-send-email-michel@daenzer.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Am 04.02.2015 um 02:19 schrieb Michel Dänzer: > From: Michel Dänzer <michel.daenzer@amd.com> > > Doing so can cause things to become slow. > > Print a warning at compile time and an informative message at runtime in > that case. > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=88758 > Cc: stable@vger.kernel.org > Signed-off-by: Michel Dänzer <michel.daenzer@amd.com> Interesting I wonder what the rational behind this is. I mean CONFIG_X86_PAT will obviously affect write combining, but why does it slow down things if we request something that the kernel isn't configured for? Anyway, patch is Reviewed-by: Christian König <christian.koenig@amd.com> Regards, Christian. > --- > drivers/gpu/drm/radeon/radeon_object.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/gpu/drm/radeon/radeon_object.c b/drivers/gpu/drm/radeon/radeon_object.c > index 7d68223..bd3df10 100644 > --- a/drivers/gpu/drm/radeon/radeon_object.c > +++ b/drivers/gpu/drm/radeon/radeon_object.c > @@ -238,6 +238,18 @@ int radeon_bo_create(struct radeon_device *rdev, > * See https://bugs.freedesktop.org/show_bug.cgi?id=84627 > */ > bo->flags &= ~RADEON_GEM_GTT_WC; > +#elif defined(CONFIG_X86) && !defined(CONFIG_X86_PAT) > + /* Don't try to enable write-combining when it can't work, or things > + * may be slow > + * See https://bugs.freedesktop.org/show_bug.cgi?id=88758 > + */ > + > +#warning Please enable CONFIG_MTRR and CONFIG_X86_PAT for better performance \ > + thanks to write-combining > + > + DRM_INFO_ONCE("Please enable CONFIG_MTRR and CONFIG_X86_PAT for " > + "better performance thanks to write-combining\n"); > + bo->flags &= ~RADEON_GEM_GTT_WC; > #endif > > radeon_ttm_placement_from_domain(bo, domain);
On Wed, Feb 4, 2015 at 4:49 AM, Christian König <deathsimple@vodafone.de> wrote: > Am 04.02.2015 um 02:19 schrieb Michel Dänzer: >> >> From: Michel Dänzer <michel.daenzer@amd.com> >> >> Doing so can cause things to become slow. >> >> Print a warning at compile time and an informative message at runtime in >> that case. >> >> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=88758 >> Cc: stable@vger.kernel.org >> Signed-off-by: Michel Dänzer <michel.daenzer@amd.com> > > > Interesting I wonder what the rational behind this is. I mean CONFIG_X86_PAT > will obviously affect write combining, but why does it slow down things if > we request something that the kernel isn't configured for? > > Anyway, patch is Reviewed-by: Christian König <christian.koenig@amd.com> Applied to my 3.20 tree. Thanks! Alex > > Regards, > Christian. > > >> --- >> drivers/gpu/drm/radeon/radeon_object.c | 12 ++++++++++++ >> 1 file changed, 12 insertions(+) >> >> diff --git a/drivers/gpu/drm/radeon/radeon_object.c >> b/drivers/gpu/drm/radeon/radeon_object.c >> index 7d68223..bd3df10 100644 >> --- a/drivers/gpu/drm/radeon/radeon_object.c >> +++ b/drivers/gpu/drm/radeon/radeon_object.c >> @@ -238,6 +238,18 @@ int radeon_bo_create(struct radeon_device *rdev, >> * See https://bugs.freedesktop.org/show_bug.cgi?id=84627 >> */ >> bo->flags &= ~RADEON_GEM_GTT_WC; >> +#elif defined(CONFIG_X86) && !defined(CONFIG_X86_PAT) >> + /* Don't try to enable write-combining when it can't work, or >> things >> + * may be slow >> + * See https://bugs.freedesktop.org/show_bug.cgi?id=88758 >> + */ >> + >> +#warning Please enable CONFIG_MTRR and CONFIG_X86_PAT for better >> performance \ >> + thanks to write-combining >> + >> + DRM_INFO_ONCE("Please enable CONFIG_MTRR and CONFIG_X86_PAT for " >> + "better performance thanks to write-combining\n"); >> + bo->flags &= ~RADEON_GEM_GTT_WC; >> #endif >> radeon_ttm_placement_from_domain(bo, domain); > > > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/dri-devel
On 04.02.2015 18:49, Christian König wrote: > Am 04.02.2015 um 02:19 schrieb Michel Dänzer: >> From: Michel Dänzer <michel.daenzer@amd.com> >> >> Doing so can cause things to become slow. >> >> Print a warning at compile time and an informative message at runtime in >> that case. >> >> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=88758 >> Cc: stable@vger.kernel.org >> Signed-off-by: Michel Dänzer <michel.daenzer@amd.com> > > Interesting I wonder what the rational behind this is. I mean > CONFIG_X86_PAT will obviously affect write combining, but why does it > slow down things if we request something that the kernel isn't > configured for? Yeah, I'm not sure exactly what happens in that case, but I don't care too much, since PAT is clearly desirable anyway. > Anyway, patch is Reviewed-by: Christian König <christian.koenig@amd.com> Thanks!
diff --git a/drivers/gpu/drm/radeon/radeon_object.c b/drivers/gpu/drm/radeon/radeon_object.c index 7d68223..bd3df10 100644 --- a/drivers/gpu/drm/radeon/radeon_object.c +++ b/drivers/gpu/drm/radeon/radeon_object.c @@ -238,6 +238,18 @@ int radeon_bo_create(struct radeon_device *rdev, * See https://bugs.freedesktop.org/show_bug.cgi?id=84627 */ bo->flags &= ~RADEON_GEM_GTT_WC; +#elif defined(CONFIG_X86) && !defined(CONFIG_X86_PAT) + /* Don't try to enable write-combining when it can't work, or things + * may be slow + * See https://bugs.freedesktop.org/show_bug.cgi?id=88758 + */ + +#warning Please enable CONFIG_MTRR and CONFIG_X86_PAT for better performance \ + thanks to write-combining + + DRM_INFO_ONCE("Please enable CONFIG_MTRR and CONFIG_X86_PAT for " + "better performance thanks to write-combining\n"); + bo->flags &= ~RADEON_GEM_GTT_WC; #endif radeon_ttm_placement_from_domain(bo, domain);