| Message ID | 1429024125-7859-1-git-send-email-chris@chris-wilson.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Apr 14, 2015 at 04:08:44PM +0100, Chris Wilson wrote: > Convert the bo-cache into 2 phases: > > 1. A two second cache of recently used buffers, keep untouched. > 2. A two second cache of older buffers, marked for eviction. > > This helps reduce ioctl traffic on a rapid turnover in working sets. The > issue is that even a 2 second window is enough for an application to > fill all of memory with inactive buffers (and we would rely on the > oom-killer identifying the right culprit). > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch> > Cc: Ben Widawsky <benjamin.widawsky@intel.com> > --- > intel/intel_bufmgr_gem.c | 42 +++++++++++++++++++++++++++++++++++------- > 1 file changed, 35 insertions(+), 7 deletions(-) > > diff --git a/intel/intel_bufmgr_gem.c b/intel/intel_bufmgr_gem.c > index f5d6130..ecbf8ee 100644 > --- a/intel/intel_bufmgr_gem.c > +++ b/intel/intel_bufmgr_gem.c > @@ -211,6 +211,11 @@ struct _drm_intel_bo_gem { > bool used_as_reloc_target; > > /** > + * Are we keeping this buffer around in semi-permenant cache? > + */ > + bool dontneed; > + > + /** > * Boolean of whether we have encountered an error whilst building the relocation tree. > */ > bool has_error; > @@ -714,7 +719,8 @@ retry: > } > > if (alloc_from_cache) { > - if (!drm_intel_gem_bo_madvise_internal > + if (bo_gem->dontneed && > + !drm_intel_gem_bo_madvise_internal > (bufmgr_gem, bo_gem, I915_MADV_WILLNEED)) { > drm_intel_gem_bo_free(&bo_gem->bo); > drm_intel_gem_bo_cache_purge_bucket(bufmgr_gem, > @@ -1150,6 +1156,20 @@ drm_intel_gem_bo_mark_mmaps_incoherent(drm_intel_bo *bo) > #endif > } > > +static inline void __splice(const drmMMListHead *list, > + drmMMListHead *prev, > + drmMMListHead *next) > +{ > + drmMMListHead *first = list->next; > + drmMMListHead *last = list->prev; > + > + first->prev = prev; > + prev->next = first; > + > + last->next = next; > + next->prev = last; > +} > + Seems worth adding to libdrm_lists.h > /** Frees all cached buffers significantly older than @time. */ > static void > drm_intel_gem_cleanup_bo_cache(drm_intel_bufmgr_gem *bufmgr_gem, time_t time) > @@ -1162,19 +1182,29 @@ drm_intel_gem_cleanup_bo_cache(drm_intel_bufmgr_gem *bufmgr_gem, time_t time) > for (i = 0; i < bufmgr_gem->num_buckets; i++) { > struct drm_intel_gem_bo_bucket *bucket = > &bufmgr_gem->cache_bucket[i]; > + drmMMListHead madv; > > + DRMINITLISTHEAD(&madv); > while (!DRMLISTEMPTY(&bucket->head)) { > drm_intel_bo_gem *bo_gem; > > bo_gem = DRMLISTENTRY(drm_intel_bo_gem, > bucket->head.next, head); > - if (time - bo_gem->free_time <= 1) > + if (time - bo_gem->free_time < 2*(1+bo_gem->dontneed)) Something somewhere will complain about mixing bools and ints, I'd guess. Also perhaps for perf bisection maybe do a patch before this changing the expiration time to 2 (or 4), then add the extra dontneed state? > break; > > DRMLISTDEL(&bo_gem->head); > - > - drm_intel_gem_bo_free(&bo_gem->bo); > + if (bo_gem->dontneed) { > + drm_intel_gem_bo_free(&bo_gem->bo); > + } else { > + drm_intel_gem_bo_madvise_internal(bufmgr_gem, bo_gem, > + I915_MADV_DONTNEED); > + bo_gem->dontneed = 1; > + DRMLISTADDTAIL(&bo_gem->head, &madv); > + } > } Maybe add a comment here? /* Objects which have elapsed 2s of disuse should go to the top of the bucket. */ > + if (!DRMLISTEMPTY(&madv)) > + __splice(&madv, &bucket->head, bucket->head.next); > } > > bufmgr_gem->time = time; > @@ -1285,9 +1315,7 @@ drm_intel_gem_bo_unreference_final(drm_intel_bo *bo, time_t time) > > bucket = drm_intel_gem_bo_bucket_for_size(bufmgr_gem, bo->size); > /* Put the buffer into our internal cache for reuse if we can. */ > - if (bufmgr_gem->bo_reuse && bo_gem->reusable && bucket != NULL && > - drm_intel_gem_bo_madvise_internal(bufmgr_gem, bo_gem, > - I915_MADV_DONTNEED)) { > + if (bufmgr_gem->bo_reuse && bo_gem->reusable && bucket != NULL) { > bo_gem->free_time = time; > > bo_gem->name = NULL; In general, it looks fine to me. Like I said above wrt adding the patch before this, I am curious how much difference you see just messing with the expiration times versus the two state model.
On Tue, Apr 14, 2015 at 12:38:56PM -0700, Ben Widawsky wrote: > > /** Frees all cached buffers significantly older than @time. */ > > static void > > drm_intel_gem_cleanup_bo_cache(drm_intel_bufmgr_gem *bufmgr_gem, time_t time) > > @@ -1162,19 +1182,29 @@ drm_intel_gem_cleanup_bo_cache(drm_intel_bufmgr_gem *bufmgr_gem, time_t time) > > for (i = 0; i < bufmgr_gem->num_buckets; i++) { > > struct drm_intel_gem_bo_bucket *bucket = > > &bufmgr_gem->cache_bucket[i]; > > + drmMMListHead madv; > > > > + DRMINITLISTHEAD(&madv); > > while (!DRMLISTEMPTY(&bucket->head)) { > > drm_intel_bo_gem *bo_gem; > > > > bo_gem = DRMLISTENTRY(drm_intel_bo_gem, > > bucket->head.next, head); > > - if (time - bo_gem->free_time <= 1) > > + if (time - bo_gem->free_time < 2*(1+bo_gem->dontneed)) > > Something somewhere will complain about mixing bools and ints, I'd guess. > > Also perhaps for perf bisection maybe do a patch before this changing the > expiration time to 2 (or 4), then add the extra dontneed state? It is already 2, since it uses <= and the patch just converts it to < to be consistent after the multiplication. > > break; > > > > DRMLISTDEL(&bo_gem->head); > > - > > - drm_intel_gem_bo_free(&bo_gem->bo); > > + if (bo_gem->dontneed) { > > + drm_intel_gem_bo_free(&bo_gem->bo); > > + } else { > > + drm_intel_gem_bo_madvise_internal(bufmgr_gem, bo_gem, > > + I915_MADV_DONTNEED); > > + bo_gem->dontneed = 1; > > + DRMLISTADDTAIL(&bo_gem->head, &madv); > > + } > > } > > Maybe add a comment here? > /* Objects which have elapsed 2s of disuse should go to the top of the bucket. */ > > > + if (!DRMLISTEMPTY(&madv)) > > + __splice(&madv, &bucket->head, bucket->head.next); > > > > } > > > > bufmgr_gem->time = time; > > @@ -1285,9 +1315,7 @@ drm_intel_gem_bo_unreference_final(drm_intel_bo *bo, time_t time) > > > > bucket = drm_intel_gem_bo_bucket_for_size(bufmgr_gem, bo->size); > > /* Put the buffer into our internal cache for reuse if we can. */ > > - if (bufmgr_gem->bo_reuse && bo_gem->reusable && bucket != NULL && > > - drm_intel_gem_bo_madvise_internal(bufmgr_gem, bo_gem, > > - I915_MADV_DONTNEED)) { > > + if (bufmgr_gem->bo_reuse && bo_gem->reusable && bucket != NULL) { > > bo_gem->free_time = time; > > > > bo_gem->name = NULL; > > In general, it looks fine to me. Like I said above wrt adding the patch before > this, I am curious how much difference you see just messing with the expiration > times versus the two state model. The issue I was looking at was simply struct_mutex contention in madvise (then busy). For busy we can tweak the ordering to reduce the contention slightly, but madvise is trickier (though madvise is a candidate for one of the first per-object locks). This just moves the contention elsewhere, but madvise/busy calls tend to dominate overall and trimming them reduces the intersection. -Chris
diff --git a/intel/intel_bufmgr_gem.c b/intel/intel_bufmgr_gem.c index f5d6130..ecbf8ee 100644 --- a/intel/intel_bufmgr_gem.c +++ b/intel/intel_bufmgr_gem.c @@ -211,6 +211,11 @@ struct _drm_intel_bo_gem { bool used_as_reloc_target; /** + * Are we keeping this buffer around in semi-permenant cache? + */ + bool dontneed; + + /** * Boolean of whether we have encountered an error whilst building the relocation tree. */ bool has_error; @@ -714,7 +719,8 @@ retry: } if (alloc_from_cache) { - if (!drm_intel_gem_bo_madvise_internal + if (bo_gem->dontneed && + !drm_intel_gem_bo_madvise_internal (bufmgr_gem, bo_gem, I915_MADV_WILLNEED)) { drm_intel_gem_bo_free(&bo_gem->bo); drm_intel_gem_bo_cache_purge_bucket(bufmgr_gem, @@ -1150,6 +1156,20 @@ drm_intel_gem_bo_mark_mmaps_incoherent(drm_intel_bo *bo) #endif } +static inline void __splice(const drmMMListHead *list, + drmMMListHead *prev, + drmMMListHead *next) +{ + drmMMListHead *first = list->next; + drmMMListHead *last = list->prev; + + first->prev = prev; + prev->next = first; + + last->next = next; + next->prev = last; +} + /** Frees all cached buffers significantly older than @time. */ static void drm_intel_gem_cleanup_bo_cache(drm_intel_bufmgr_gem *bufmgr_gem, time_t time) @@ -1162,19 +1182,29 @@ drm_intel_gem_cleanup_bo_cache(drm_intel_bufmgr_gem *bufmgr_gem, time_t time) for (i = 0; i < bufmgr_gem->num_buckets; i++) { struct drm_intel_gem_bo_bucket *bucket = &bufmgr_gem->cache_bucket[i]; + drmMMListHead madv; + DRMINITLISTHEAD(&madv); while (!DRMLISTEMPTY(&bucket->head)) { drm_intel_bo_gem *bo_gem; bo_gem = DRMLISTENTRY(drm_intel_bo_gem, bucket->head.next, head); - if (time - bo_gem->free_time <= 1) + if (time - bo_gem->free_time < 2*(1+bo_gem->dontneed)) break; DRMLISTDEL(&bo_gem->head); - - drm_intel_gem_bo_free(&bo_gem->bo); + if (bo_gem->dontneed) { + drm_intel_gem_bo_free(&bo_gem->bo); + } else { + drm_intel_gem_bo_madvise_internal(bufmgr_gem, bo_gem, + I915_MADV_DONTNEED); + bo_gem->dontneed = 1; + DRMLISTADDTAIL(&bo_gem->head, &madv); + } } + if (!DRMLISTEMPTY(&madv)) + __splice(&madv, &bucket->head, bucket->head.next); } bufmgr_gem->time = time; @@ -1285,9 +1315,7 @@ drm_intel_gem_bo_unreference_final(drm_intel_bo *bo, time_t time) bucket = drm_intel_gem_bo_bucket_for_size(bufmgr_gem, bo->size); /* Put the buffer into our internal cache for reuse if we can. */ - if (bufmgr_gem->bo_reuse && bo_gem->reusable && bucket != NULL && - drm_intel_gem_bo_madvise_internal(bufmgr_gem, bo_gem, - I915_MADV_DONTNEED)) { + if (bufmgr_gem->bo_reuse && bo_gem->reusable && bucket != NULL) { bo_gem->free_time = time; bo_gem->name = NULL;
Convert the bo-cache into 2 phases: 1. A two second cache of recently used buffers, keep untouched. 2. A two second cache of older buffers, marked for eviction. This helps reduce ioctl traffic on a rapid turnover in working sets. The issue is that even a 2 second window is enough for an application to fill all of memory with inactive buffers (and we would rely on the oom-killer identifying the right culprit). Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Ben Widawsky <benjamin.widawsky@intel.com> --- intel/intel_bufmgr_gem.c | 42 +++++++++++++++++++++++++++++++++++------- 1 file changed, 35 insertions(+), 7 deletions(-)