[PATCH 15/15] drm/msm/gem: Evict active GEM objects when necessary

Rob Clark
2022-06-25T22:55:58Z

If we are under enough memory pressure, we should stall waiting for
active buffers to become idle in order to evict.

Signed-off-by: Rob Clark <robdclark@chromium.org>
---
drivers/gpu/drm/msm/msm_gem_shrinker.c | 68 +++++++++++++++++++++-----
drivers/gpu/drm/msm/msm_gpu_trace.h | 16 +++---
2 files changed, 66 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gem_shrinker.c b/drivers/gpu/drm/msm/msm_gem_shrinker.c
index 5cc05d669a08..b0bee040432a 100644
--- a/drivers/gpu/drm/msm/msm_gem_shrinker.c
+++ b/drivers/gpu/drm/msm/msm_gem_shrinker.c
@@ -24,6 +24,11 @@ static bool can_swap(void)
return enable_eviction && get_nr_swap_pages() > 0;
}

+static bool can_block(struct shrink_control *sc)
+{
+ return current_is_kswapd() || (sc->gfp_mask & __GFP_RECLAIM);
+}
+
static unsigned long
msm_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
{
@@ -65,26 +70,65 @@ evict(struct drm_gem_object *obj)
return true;
}

+static bool
+wait_for_idle(struct drm_gem_object *obj)
+{
+ enum dma_resv_usage usage = dma_resv_usage_rw(true);
+ return dma_resv_wait_timeout(obj->resv, usage, false, 1000) > 0;
+}
+
+static bool
+active_purge(struct drm_gem_object *obj)
+{
+ if (!wait_for_idle(obj))
+ return false;
+
+ return purge(obj);
+}
+
+static bool
+active_evict(struct drm_gem_object *obj)
+{
+ if (!wait_for_idle(obj))
+ return false;
+
+ return evict(obj);
+}
+
static unsigned long
msm_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
{
struct msm_drm_private *priv =
container_of(shrinker, struct msm_drm_private, shrinker);
+ struct {
+ struct drm_gem_lru *lru;
+ bool (*shrink)(struct drm_gem_object *obj);
+ bool cond;
+ unsigned long freed;
+ } stages[] = {
+ /* Stages of progressively more aggressive/expensive reclaim: */
+ { &priv->lru.dontneed, purge, true },
+ { &priv->lru.willneed, evict, can_swap() },
+ { &priv->lru.dontneed, active_purge, can_block(sc) },
+ { &priv->lru.willneed, active_evict, can_swap() && can_block(sc) },
+ };
long nr = sc->nr_to_scan;
- unsigned long freed, purged, evicted = 0;
-
- purged = drm_gem_lru_scan(&priv->lru.dontneed, nr, purge);
- nr -= purged;
-
- if (can_swap() && nr > 0) {
- evicted = drm_gem_lru_scan(&priv->lru.willneed, nr, evict);
- nr -= evicted;
+ unsigned long freed = 0;
+
+ for (unsigned i = 0; (nr > 0) && (i < ARRAY_SIZE(stages)); i++) {
+ if (!stages[i].cond)
+ continue;
+ stages[i].freed =
+ drm_gem_lru_scan(stages[i].lru, nr, stages[i].shrink);
+ nr -= stages[i].freed;
+ freed += stages[i].freed;
}

- freed = purged + evicted;
-
- if (freed)
- trace_msm_gem_shrink(sc->nr_to_scan, purged, evicted);
+ if (freed) {
+ trace_msm_gem_shrink(sc->nr_to_scan, stages[0].freed,
+ stages[1].freed, stages[2].freed,
+ stages[3].freed);
+ }

return (freed > 0) ? freed : SHRINK_STOP;
}
diff --git a/drivers/gpu/drm/msm/msm_gpu_trace.h b/drivers/gpu/drm/msm/msm_gpu_trace.h
index 8867fa0a0306..ac40d857bc45 100644
--- a/drivers/gpu/drm/msm/msm_gpu_trace.h
+++ b/drivers/gpu/drm/msm/msm_gpu_trace.h
@@ -116,22 +116,26 @@ TRACE_EVENT(msm_gmu_freq_change,

TRACE_EVENT(msm_gem_shrink,
- TP_PROTO(u32 nr_to_scan, u32 purged, u32 evicted),
- TP_ARGS(nr_to_scan, purged, evicted),
+ TP_PROTO(u32 nr_to_scan, u32 purged, u32 evicted,
+ u32 active_purged, u32 active_evicted),
+ TP_ARGS(nr_to_scan, purged, evicted, active_purged, active_evicted),
TP_STRUCT__entry(
__field(u32, nr_to_scan)
__field(u32, purged)
__field(u32, evicted)
+ __field(u32, active_purged)
+ __field(u32, active_evicted)
),
TP_fast_assign(
__entry->nr_to_scan = nr_to_scan;
__entry->purged = purged;
__entry->evicted = evicted;
+ __entry->active_purged = active_purged;
+ __entry->active_evicted = active_evicted;
),
- TP_printk("nr_to_scan=%u pages, purged=%u pages, evicted=%u pages",
- __entry->nr_to_scan,
- __entry->purged,
- __entry->evicted)
+ TP_printk("nr_to_scan=%u pg, purged=%u pg, evicted=%u pg, active_purged=%u pg, active_evicted=%u pg",
+ __entry->nr_to_scan, __entry->purged, __entry->evicted,
+ __entry->active_purged, __entry->active_evicted)
);

--
2.36.1