On ma, 2017-03-06 at 09:29 +0000, Chris Wilson wrote: > Before we instantiate/pin the backing store for our use, we > can prepopulate the shmemfs filp efficiently using the a > write into the pagecache. We avoid the penalty of instantiating > all the pages, important if the user is just writing to a few > and never uses the object on the GPU, and using a direct write > into shmemfs allows it to avoid the cost of retrieving a page > (either swapin or clearing-before-use) before it is overwritten. > > This can be extended later to provide additional specialisation for > other backends (other than shmemfs). > > References: https://bugs.freedesktop.org/show_bug.cgi?id=99107 > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > Cc: Matthew Auld <matthew.william.auld@xxxxxxxxx> > Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx> > Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx> <SNIP> > +static int > +i915_gem_object_pwrite_gtt(struct drm_i915_gem_object *obj, > + const struct drm_i915_gem_pwrite *arg) > +{ > + struct address_space *mapping = obj->base.filp->f_mapping; > + char __user *user_data = u64_to_user_ptr(arg->data_ptr); > + u64 remain, offset; > + unsigned int pg; > + > + /* Before we instantiate/pin the backing store for our use, we > + * can prepopulate the shmemfs filp efficiently using the a > + * write into the pagecache. We avoid the penalty of instantiating > + * all the pages, important if the user is just writing to a few > + * and never uses the object on the GPU, and using a direct write > + * into shmemfs allows it to avoid the cost of retrieving a page > + * (either swapin or clearing-before-use) before it is overwritten. > + */ > + if (READ_ONCE(obj->mm.pages)) > + return -ENODEV; > + > + /* Before the pages are instantioted the object is treated as being *instantiated <SNIP> > + err = pagecache_write_end(obj->base.filp, mapping, offset, > + len, len - unwritten, > + page, data); Did you deliberately make the arguments different from write_begin? :) If this solves a problem; Reviewed-by: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx> But should we instead fix libva? Regards, Joonas -- Joonas Lahtinen Open Source Technology Center Intel Corporation _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
