From mboxrd@z Thu Jan 1 00:00:00 1970 From: Robert Beckett Subject: Re: [PATCH 4/4] drm/i915: Invalidate our pages under memory pressure Date: Wed, 16 Apr 2014 18:13:36 +0100 Message-ID: <534EBA40.3080909@intel.com> References: <1395753786-6442-1-git-send-email-chris@chris-wilson.co.uk> <1395753786-6442-4-git-send-email-chris@chris-wilson.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by gabe.freedesktop.org (Postfix) with ESMTP id 10AC28959D for ; Wed, 16 Apr 2014 10:27:47 -0700 (PDT) In-Reply-To: <1395753786-6442-4-git-send-email-chris@chris-wilson.co.uk> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" To: Chris Wilson , intel-gfx@lists.freedesktop.org Cc: Hugh Dickins List-Id: intel-gfx@lists.freedesktop.org On 25/03/2014 13:23, Chris Wilson wrote: > Try to flush out dirty pages into the swapcache (and from there into the > swapfile) when under memory pressure and forced to drop GEM objects from > memory. In effect, this should just allow us to discard unused pages for > memory reclaim and to start writeback earlier. > > v2: Hugh Dickins warned that explicitly starting writeback from > shrink_slab was prone to deadlocks within shmemfs. > > Cc: Hugh Dickins > Signed-off-by: Chris Wilson > --- > drivers/gpu/drm/i915/i915_gem.c | 38 +++++++++++++++++++++++++++----------- > 1 file changed, 27 insertions(+), 11 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c > index 135ee8bd55f6..8287fd6701c6 100644 > --- a/drivers/gpu/drm/i915/i915_gem.c > +++ b/drivers/gpu/drm/i915/i915_gem.c > @@ -60,7 +60,6 @@ static unsigned long i915_gem_shrinker_scan(struct shrinker *shrinker, > struct shrink_control *sc); > static unsigned long i915_gem_purge(struct drm_i915_private *dev_priv, long target); > static unsigned long i915_gem_shrink_all(struct drm_i915_private *dev_priv); > -static void i915_gem_object_truncate(struct drm_i915_gem_object *obj); > static void i915_gem_retire_requests_ring(struct intel_ring_buffer *ring); > > static bool cpu_cache_is_coherent(struct drm_device *dev, > @@ -1685,12 +1684,16 @@ i915_gem_mmap_gtt_ioctl(struct drm_device *dev, void *data, > return i915_gem_mmap_gtt(file, dev, args->handle, &args->offset); > } > > +static inline int > +i915_gem_object_is_purgeable(struct drm_i915_gem_object *obj) > +{ > + return obj->madv == I915_MADV_DONTNEED; > +} > + > /* Immediately discard the backing storage */ > static void > i915_gem_object_truncate(struct drm_i915_gem_object *obj) > { > - struct inode *inode; > - > i915_gem_object_free_mmap_offset(obj); > > if (obj->base.filp == NULL) > @@ -1701,16 +1704,28 @@ i915_gem_object_truncate(struct drm_i915_gem_object *obj) > * To do this we must instruct the shmfs to drop all of its > * backing pages, *now*. > */ > - inode = file_inode(obj->base.filp); > - shmem_truncate_range(inode, 0, (loff_t)-1); > - > + shmem_truncate_range(file_inode(obj->base.filp), 0, (loff_t)-1); > obj->madv = __I915_MADV_PURGED; > } > > -static inline int > -i915_gem_object_is_purgeable(struct drm_i915_gem_object *obj) > +/* Try to discard unwanted pages */ > +static void > +i915_gem_object_invalidate(struct drm_i915_gem_object *obj) > { > - return obj->madv == I915_MADV_DONTNEED; > + struct address_space *mapping; > + > + switch (obj->madv) { > + case I915_MADV_DONTNEED: > + i915_gem_object_truncate(obj); > + case __I915_MADV_PURGED: > + return; > + } > + > + if (obj->base.filp == NULL) > + return; > + > + mapping = file_inode(obj->base.filp)->i_mapping, > + invalidate_mapping_pages(mapping, 0, (loff_t)-1); > } > > static void > @@ -1775,8 +1790,7 @@ i915_gem_object_put_pages(struct drm_i915_gem_object *obj) > ops->put_pages(obj); > obj->pages = NULL; > > - if (i915_gem_object_is_purgeable(obj)) > - i915_gem_object_truncate(obj); > + i915_gem_object_invalidate(obj); > > return 0; > } > @@ -4201,6 +4215,8 @@ void i915_gem_free_object(struct drm_gem_object *gem_obj) > > if (WARN_ON(obj->pages_pin_count)) > obj->pages_pin_count = 0; > + if (obj->madv != __I915_MADV_PURGED) > + obj->madv = I915_MADV_DONTNEED; > i915_gem_object_put_pages(obj); > i915_gem_object_free_mmap_offset(obj); > i915_gem_object_release_stolen(obj); > Functionally it looks good to me. Though, you may want a /* fall-through */ comment (some people cant mentally parse fallthroughs without being prompted) and a default: break; (to avoid any static code analysis complaints) in the switch in i915_gem_object_invalidate. Reviewed-by: Robert Beckett