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 at chris-wilson.co.uk> wrote: > > On Tue, 9 Oct 2012 22:50:48 +0200, Daniel Vetter <daniel.vetter at 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 at lists.freedesktop.org > > http://lists.freedesktop.org/mailman/listinfo/intel-gfx > From: Chris Wilson <chris at chris-wilson.co.uk> > Subject: Re: [PATCH] drm/i915: fixup i915_gem_object_get_page inline helper > To: Daniel Vetter <daniel.vetter at ffwll.ch>, Intel Graphics Development <intel-gfx at lists.freedesktop.org> > Cc: Daniel Vetter <daniel.vetter at ffwll.ch> > In-Reply-To: <1349815848-1824-1-git-send-email-daniel.vetter at ffwll.ch> > References: <84c8a8$624sk4 at orsmga001.jf.intel.com> <1349815848-1824-1-git-send-email-daniel.vetter at ffwll.ch> > > On Tue, 9 Oct 2012 22:50:48 +0200, Daniel Vetter <daniel.vetter at 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 at 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 -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch
