From f2d476a110bc24fde008698ae9018c99e803e25c Mon Sep 17 00:00:00 2001 From: Maarten Lankhorst Date: Tue, 15 Jan 2013 14:57:10 +0100 Subject: [PATCH] drm/ttm: use ttm_bo_reserve_slowpath_nolru in ttm_eu_reserve_buffers, v2 This requires re-use of the seqno, which increases fairness slightly. Instead of spinning with a new seqno every time we keep the current one, but still drop all other reservations we hold. Only when we succeed, we try to get back our other reservations again. This should increase fairness slightly as well. Changes since v1: - Increase val_seq before calling ttm_bo_reserve_slowpath_nolru and retrying to take all entries to prevent a race. Signed-off-by: Maarten Lankhorst Reviewed-by: Jerome Glisse --- drivers/gpu/drm/ttm/ttm_execbuf_util.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/ttm/ttm_execbuf_util.c b/drivers/gpu/drm/ttm/ttm_execbuf_util.c index c7d323657798..7b90def15674 100644 --- a/drivers/gpu/drm/ttm/ttm_execbuf_util.c +++ b/drivers/gpu/drm/ttm/ttm_execbuf_util.c @@ -129,13 +129,17 @@ int ttm_eu_reserve_buffers(struct list_head *list) entry = list_first_entry(list, struct ttm_validate_buffer, head); glob = entry->bo->glob; -retry: spin_lock(&glob->lru_lock); val_seq = entry->bo->bdev->val_seq++; +retry: list_for_each_entry(entry, list, head) { struct ttm_buffer_object *bo = entry->bo; + /* already slowpath reserved? */ + if (entry->reserved) + continue; + ret = ttm_bo_reserve_nolru(bo, true, true, true, val_seq); switch (ret) { case 0: @@ -155,11 +159,26 @@ retry: /* fallthrough */ case -EAGAIN: ttm_eu_backoff_reservation_locked(list); + + /* + * temporarily increase sequence number every retry, + * to prevent us from seeing our old reservation + * sequence when someone else reserved the buffer, + * but hasn't updated the seq_valid/seqno members yet. + */ + val_seq = entry->bo->bdev->val_seq++; + spin_unlock(&glob->lru_lock); ttm_eu_list_ref_sub(list); - ret = ttm_bo_wait_unreserved(bo, true); + ret = ttm_bo_reserve_slowpath_nolru(bo, true, val_seq); if (unlikely(ret != 0)) return ret; + spin_lock(&glob->lru_lock); + entry->reserved = true; + if (unlikely(atomic_read(&bo->cpu_writers) > 0)) { + ret = -EBUSY; + goto err; + } goto retry; default: goto err; -- 2.20.1