| Message ID | 1349815848-1824-1-git-send-email-daniel.vetter@ffwll.ch (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, 9 Oct 2012 22:50:48 +0200, Daniel Vetter <daniel.vetter@ffwll.ch> wrote: > The obj->pages to obj->pages->sgl rework introduced this helper, but > it doesn't actually work for n >= SG_MAX_SINGLE_ALLOC. > > For simplicity (and since right now I seem to be too stupid to see > the bug), let's just grab the right page with a for_each_sg loop. > > This is exercised by the improved hangman tests and the gem_exec_big > test in i-g-t. > > v2: Compared to v1, don't try to be clever since I seemingly only > manage to prove that I'm not clever. Only I expect that loop to show up on profiles even higher than the sg_next() from pwrite. :| I expect it to have a measureable impact upon relocation throughput, so I should measure it... -Chris
On Tue, 09 Oct 2012 23:16:02 +0100, Chris Wilson <chris@chris-wilson.co.uk> wrote: > On Tue, 9 Oct 2012 22:50:48 +0200, Daniel Vetter <daniel.vetter@ffwll.ch> wrote: > > The obj->pages to obj->pages->sgl rework introduced this helper, but > > it doesn't actually work for n >= SG_MAX_SINGLE_ALLOC. > > > > For simplicity (and since right now I seem to be too stupid to see > > the bug), let's just grab the right page with a for_each_sg loop. > > > > This is exercised by the improved hangman tests and the gem_exec_big > > test in i-g-t. > > > > v2: Compared to v1, don't try to be clever since I seemingly only > > manage to prove that I'm not clever. > > Only I expect that loop to show up on profiles even higher than the > sg_next() from pwrite. :| > > I expect it to have a measureable impact upon relocation throughput, > so I should measure it... > -Chris > > -- > Chris Wilson, Intel Open Source Technology Centre > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/intel-gfx From: Chris Wilson <chris@chris-wilson.co.uk> Subject: Re: [PATCH] drm/i915: fixup i915_gem_object_get_page inline helper To: Daniel Vetter <daniel.vetter@ffwll.ch>, Intel Graphics Development <intel-gfx@lists.freedesktop.org> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> In-Reply-To: <1349815848-1824-1-git-send-email-daniel.vetter@ffwll.ch> References: <84c8a8$624sk4@orsmga001.jf.intel.com> <1349815848-1824-1-git-send-email-daniel.vetter@ffwll.ch> On Tue, 9 Oct 2012 22:50:48 +0200, Daniel Vetter <daniel.vetter@ffwll.ch> wrote: > The obj->pages to obj->pages->sgl rework introduced this helper, but > it doesn't actually work for n >= SG_MAX_SINGLE_ALLOC. > > For simplicity (and since right now I seem to be too stupid to see > the bug), let's just grab the right page with a for_each_sg loop. > > This is exercised by the improved hangman tests and the gem_exec_big > test in i-g-t. > > v2: Compared to v1, don't try to be clever since I seemingly only > manage to prove that I'm not clever. > > Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Looks like my worries are baseless. It can always be attacked latter if need be. I'd still like to know what the mistake was... Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> -Chris
On Wed, Oct 10, 2012 at 10:01:47AM +0100, Chris Wilson wrote: > On Tue, 09 Oct 2012 23:16:02 +0100, Chris Wilson <chris@chris-wilson.co.uk> wrote: > > On Tue, 9 Oct 2012 22:50:48 +0200, Daniel Vetter <daniel.vetter@ffwll.ch> wrote: > > > The obj->pages to obj->pages->sgl rework introduced this helper, but > > > it doesn't actually work for n >= SG_MAX_SINGLE_ALLOC. > > > > > > For simplicity (and since right now I seem to be too stupid to see > > > the bug), let's just grab the right page with a for_each_sg loop. > > > > > > This is exercised by the improved hangman tests and the gem_exec_big > > > test in i-g-t. > > > > > > v2: Compared to v1, don't try to be clever since I seemingly only > > > manage to prove that I'm not clever. > > > > Only I expect that loop to show up on profiles even higher than the > > sg_next() from pwrite. :| > > > > I expect it to have a measureable impact upon relocation throughput, > > so I should measure it... > > -Chris > > > > -- > > Chris Wilson, Intel Open Source Technology Centre > > _______________________________________________ > > Intel-gfx mailing list > > Intel-gfx@lists.freedesktop.org > > http://lists.freedesktop.org/mailman/listinfo/intel-gfx > From: Chris Wilson <chris@chris-wilson.co.uk> > Subject: Re: [PATCH] drm/i915: fixup i915_gem_object_get_page inline helper > To: Daniel Vetter <daniel.vetter@ffwll.ch>, Intel Graphics Development <intel-gfx@lists.freedesktop.org> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > In-Reply-To: <1349815848-1824-1-git-send-email-daniel.vetter@ffwll.ch> > References: <84c8a8$624sk4@orsmga001.jf.intel.com> <1349815848-1824-1-git-send-email-daniel.vetter@ffwll.ch> > > On Tue, 9 Oct 2012 22:50:48 +0200, Daniel Vetter <daniel.vetter@ffwll.ch> wrote: > > The obj->pages to obj->pages->sgl rework introduced this helper, but > > it doesn't actually work for n >= SG_MAX_SINGLE_ALLOC. > > > > For simplicity (and since right now I seem to be too stupid to see > > the bug), let's just grab the right page with a for_each_sg loop. > > > > This is exercised by the improved hangman tests and the gem_exec_big > > test in i-g-t. > > > > v2: Compared to v1, don't try to be clever since I seemingly only > > manage to prove that I'm not clever. > > > > Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> > > Looks like my worries are baseless. It can always be attacked latter if > need be. I'd still like to know what the mistake was... I think it was two mistakes: - One was the off-by-one fixed in v1. - Second seemed to be the special case that if the table fits exactly, sg_alloc doesn't set a chain ptr with another sg table with just one entry. But like the commit message says, I've failed to be clever enough yesterday to make it work. -Daniel
On Wed, Oct 10, 2012 at 10:01:47AM +0100, Chris Wilson wrote: > On Tue, 09 Oct 2012 23:16:02 +0100, Chris Wilson <chris@chris-wilson.co.uk> wrote: > > On Tue, 9 Oct 2012 22:50:48 +0200, Daniel Vetter <daniel.vetter@ffwll.ch> wrote: > > > The obj->pages to obj->pages->sgl rework introduced this helper, but > > > it doesn't actually work for n >= SG_MAX_SINGLE_ALLOC. > > > > > > For simplicity (and since right now I seem to be too stupid to see > > > the bug), let's just grab the right page with a for_each_sg loop. > > > > > > This is exercised by the improved hangman tests and the gem_exec_big > > > test in i-g-t. > > > > > > v2: Compared to v1, don't try to be clever since I seemingly only > > > manage to prove that I'm not clever. > > > > Only I expect that loop to show up on profiles even higher than the > > sg_next() from pwrite. :| > > > > I expect it to have a measureable impact upon relocation throughput, > > so I should measure it... > > -Chris > > > > -- > > Chris Wilson, Intel Open Source Technology Centre > > _______________________________________________ > > Intel-gfx mailing list > > Intel-gfx@lists.freedesktop.org > > http://lists.freedesktop.org/mailman/listinfo/intel-gfx > From: Chris Wilson <chris@chris-wilson.co.uk> > Subject: Re: [PATCH] drm/i915: fixup i915_gem_object_get_page inline helper > To: Daniel Vetter <daniel.vetter@ffwll.ch>, Intel Graphics Development <intel-gfx@lists.freedesktop.org> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > In-Reply-To: <1349815848-1824-1-git-send-email-daniel.vetter@ffwll.ch> > References: <84c8a8$624sk4@orsmga001.jf.intel.com> <1349815848-1824-1-git-send-email-daniel.vetter@ffwll.ch> > > On Tue, 9 Oct 2012 22:50:48 +0200, Daniel Vetter <daniel.vetter@ffwll.ch> wrote: > > The obj->pages to obj->pages->sgl rework introduced this helper, but > > it doesn't actually work for n >= SG_MAX_SINGLE_ALLOC. > > > > For simplicity (and since right now I seem to be too stupid to see > > the bug), let's just grab the right page with a for_each_sg loop. > > > > This is exercised by the improved hangman tests and the gem_exec_big > > test in i-g-t. > > > > v2: Compared to v1, don't try to be clever since I seemingly only > > manage to prove that I'm not clever. > > > > Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> > > Looks like my worries are baseless. It can always be attacked latter if > need be. I'd still like to know what the mistake was... > > Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Merged to -fixes, with the missing regression-sha1 citation added. -Daniel
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 4f2831a..32a2e47 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -1340,12 +1340,14 @@ void i915_gem_lastclose(struct drm_device *dev); int __must_check i915_gem_object_get_pages(struct drm_i915_gem_object *obj); static inline struct page *i915_gem_object_get_page(struct drm_i915_gem_object *obj, int n) { - struct scatterlist *sg = obj->pages->sgl; - while (n >= SG_MAX_SINGLE_ALLOC) { - sg = sg_chain_ptr(sg + SG_MAX_SINGLE_ALLOC - 1); - n -= SG_MAX_SINGLE_ALLOC - 1; + struct scatterlist *sg; + int i; + + for_each_sg(obj->pages->sgl, sg, obj->pages->nents, i) { + if (i == n) + return sg_page(sg); } - return sg_page(sg+n); + return NULL; } static inline void i915_gem_object_pin_pages(struct drm_i915_gem_object *obj) {
The obj->pages to obj->pages->sgl rework introduced this helper, but it doesn't actually work for n >= SG_MAX_SINGLE_ALLOC. For simplicity (and since right now I seem to be too stupid to see the bug), let's just grab the right page with a for_each_sg loop. This is exercised by the improved hangman tests and the gem_exec_big test in i-g-t. v2: Compared to v1, don't try to be clever since I seemingly only manage to prove that I'm not clever. Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> --- drivers/gpu/drm/i915/i915_drv.h | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)