shrink_slab() allows us to report back the number of objects we
successfully scanned (out of the target shrinkctl->nr_to_scan). As
report the number of pages owned by each GEM object as a separate item
to the shrinker, we cannot precisely control the number of shrinker
objects we scan on each pass; and indeed may free more than requested.
If we fail to tell the shrinker about the number of objects we process,
it will continue to hold a grudge against us as any objects left
unscanned are added to the next reclaim -- and so we will keep on
"unfairly" shrinking our own slab in comparison to other slabs.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Shaohua Li <shli@xxxxxx>
Cc: linux-mm@xxxxxxxxx
---
drivers/gpu/drm/i915/i915_debugfs.c | 4 ++--
drivers/gpu/drm/i915/i915_drv.h | 1 +
drivers/gpu/drm/i915/i915_gem.c | 4 ++--
drivers/gpu/drm/i915/i915_gem_gtt.c | 2 +-
drivers/gpu/drm/i915/i915_gem_shrinker.c | 24 ++++++++++++++++++------
5 files changed, 24 insertions(+), 11 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 6bad53f89738..ed979cc6fb5d 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -4338,10 +4338,10 @@ i915_drop_caches_set(void *data, u64 val)
lockdep_set_current_reclaim_state(GFP_KERNEL);
if (val & DROP_BOUND)
- i915_gem_shrink(dev_priv, LONG_MAX, I915_SHRINK_BOUND);
+ i915_gem_shrink(dev_priv, LONG_MAX, NULL, I915_SHRINK_BOUND);
if (val & DROP_UNBOUND)
- i915_gem_shrink(dev_priv, LONG_MAX, I915_SHRINK_UNBOUND);
+ i915_gem_shrink(dev_priv, LONG_MAX, NULL, I915_SHRINK_UNBOUND);
if (val & DROP_SHRINK_ALL)
i915_gem_shrink_all(dev_priv);
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index b78605a9f1b5..c3299eaac1af 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -3752,6 +3752,7 @@ i915_gem_object_create_internal(struct drm_i915_private *dev_priv,
/* i915_gem_shrinker.c */
unsigned long i915_gem_shrink(struct drm_i915_private *dev_priv,
unsigned long target,
+ unsigned long *nr_scanned,
unsigned flags);
#define I915_SHRINK_PURGEABLE 0x1
#define I915_SHRINK_UNBOUND 0x2
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index a2714898ff01..c06091718bb4 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2339,7 +2339,7 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
goto err_sg;
}
- i915_gem_shrink(dev_priv, 2 * page_count, *s++);
+ i915_gem_shrink(dev_priv, 2 * page_count, NULL, *s++);
cond_resched();
/* We've tried hard to allocate the memory by reaping
@@ -5037,7 +5037,7 @@ int i915_gem_freeze_late(struct drm_i915_private *dev_priv)
* the objects as well, see i915_gem_freeze()
*/
- i915_gem_shrink(dev_priv, -1UL, I915_SHRINK_UNBOUND);
+ i915_gem_shrink(dev_priv, -1UL, NULL, I915_SHRINK_UNBOUND);
i915_gem_drain_freed_objects(dev_priv);
spin_lock(&dev_priv->mm.obj_lock);
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index b6d5f1c6ef5e..8394fc2a21eb 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -2062,7 +2062,7 @@ int i915_gem_gtt_prepare_pages(struct drm_i915_gem_object *obj,
*/
GEM_BUG_ON(obj->mm.pages == pages);
} while (i915_gem_shrink(to_i915(obj->base.dev),
- obj->base.size >> PAGE_SHIFT,
+ obj->base.size >> PAGE_SHIFT, NULL,
I915_SHRINK_BOUND |
I915_SHRINK_UNBOUND |
I915_SHRINK_ACTIVE));
diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c
index ee4df98f009d..c178a1c9ae47 100644
--- a/drivers/gpu/drm/i915/i915_gem_shrinker.c
+++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c
@@ -198,6 +198,7 @@ static void __start_writeback(struct drm_i915_gem_object *obj)
* i915_gem_shrink - Shrink buffer object caches
* @dev_priv: i915 device
* @target: amount of memory to make available, in pages
+ * @nr_scanned: optional output for number of pages scanned (incremental)
* @flags: control flags for selecting cache types
*
* This function is the main interface to the shrinker. It will try to release
@@ -220,7 +221,9 @@ static void __start_writeback(struct drm_i915_gem_object *obj)
*/
unsigned long
i915_gem_shrink(struct drm_i915_private *dev_priv,
- unsigned long target, unsigned flags)
+ unsigned long target,
+ unsigned long *nr_scanned,
+ unsigned flags)
{
const struct {
struct list_head *list;
@@ -231,6 +234,7 @@ i915_gem_shrink(struct drm_i915_private *dev_priv,
{ NULL, 0 },
}, *phase;
unsigned long count = 0;
+ unsigned long scanned = 0;
bool unlock;
if (!shrinker_lock(dev_priv, &unlock))
@@ -318,6 +322,7 @@ i915_gem_shrink(struct drm_i915_private *dev_priv,
}
mutex_unlock(&obj->mm.lock);
}
+ scanned += obj->base.size >> PAGE_SHIFT;
spin_lock(&dev_priv->mm.obj_lock);
}
@@ -332,6 +337,8 @@ i915_gem_shrink(struct drm_i915_private *dev_priv,
shrinker_unlock(dev_priv, unlock);
+ if (nr_scanned)
+ *nr_scanned += scanned;
return count;
}
@@ -354,7 +361,7 @@ unsigned long i915_gem_shrink_all(struct drm_i915_private *dev_priv)
unsigned long freed;
intel_runtime_pm_get(dev_priv);
- freed = i915_gem_shrink(dev_priv, -1UL,
+ freed = i915_gem_shrink(dev_priv, -1UL, NULL,
I915_SHRINK_BOUND |
I915_SHRINK_UNBOUND |
I915_SHRINK_ACTIVE);
@@ -411,23 +418,28 @@ i915_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
unsigned long freed;
bool unlock;
+ sc->nr_scanned = 0;
+
if (!shrinker_lock(dev_priv, &unlock))
return SHRINK_STOP;
freed = i915_gem_shrink(dev_priv,
sc->nr_to_scan,
+ &sc->nr_scanned,
I915_SHRINK_BOUND |
I915_SHRINK_UNBOUND |
I915_SHRINK_PURGEABLE);
if (freed < sc->nr_to_scan)
freed += i915_gem_shrink(dev_priv,
- sc->nr_to_scan - freed,
+ sc->nr_to_scan - sc->nr_scanned,
+ &sc->nr_scanned,
I915_SHRINK_BOUND |
I915_SHRINK_UNBOUND);
if (freed < sc->nr_to_scan && current_is_kswapd()) {
intel_runtime_pm_get(dev_priv);
freed += i915_gem_shrink(dev_priv,
- sc->nr_to_scan - freed,
+ sc->nr_to_scan - sc->nr_scanned,
+ &sc->nr_scanned,
I915_SHRINK_ACTIVE |
I915_SHRINK_BOUND |
I915_SHRINK_UNBOUND);
@@ -436,7 +448,7 @@ i915_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
shrinker_unlock(dev_priv, unlock);
- return freed;
+ return sc->nr_scanned ? freed : SHRINK_STOP;
}
static bool
@@ -525,7 +537,7 @@ i915_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr
goto out;
intel_runtime_pm_get(dev_priv);
- freed_pages += i915_gem_shrink(dev_priv, -1UL,
+ freed_pages += i915_gem_shrink(dev_priv, -1UL, NULL,
I915_SHRINK_BOUND |
I915_SHRINK_UNBOUND |
I915_SHRINK_ACTIVE |
--
2.14.1
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