[Intel-gfx] [PATCH 2/2] drm/i915: Wire up shrinkctl->nr_scanned
Andrew Morton
akpm at linux-foundation.org
Tue Aug 22 22:45:50 UTC 2017
On Tue, 22 Aug 2017 14:53:25 +0100 Chris Wilson <chris at chris-wilson.co.uk> wrote:
> 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.
It's unclear which tree this is against but I think I got it all fixed
up. Please check the changes to i915_gem_shrink().
From: Chris Wilson <chris at chris-wilson.co.uk>
Subject: drm/i915: wire up shrinkctl->nr_scanned
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.
Link: http://lkml.kernel.org/r/20170822135325.9191-2-chris@chris-wilson.co.uk
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Cc: Michal Hocko <mhocko at suse.com>
Cc: Johannes Weiner <hannes at cmpxchg.org>
Cc: Hillf Danton <hillf.zj at alibaba-inc.com>
Cc: Minchan Kim <minchan at kernel.org>
Cc: Vlastimil Babka <vbabka at suse.cz>
Cc: Mel Gorman <mgorman at techsingularity.net>
Cc: Shaohua Li <shli at fb.com>
Cc: Christoph Lameter <cl at linux.com>
Cc: David Rientjes <rientjes at google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim at lge.com>
Cc: Pekka Enberg <penberg at kernel.org>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
---
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 -puN drivers/gpu/drm/i915/i915_debugfs.c~drm-i915-wire-up-shrinkctl-nr_scanned drivers/gpu/drm/i915/i915_debugfs.c
--- a/drivers/gpu/drm/i915/i915_debugfs.c~drm-i915-wire-up-shrinkctl-nr_scanned
+++ a/drivers/gpu/drm/i915/i915_debugfs.c
@@ -4333,10 +4333,10 @@ 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 -puN drivers/gpu/drm/i915/i915_drv.h~drm-i915-wire-up-shrinkctl-nr_scanned drivers/gpu/drm/i915/i915_drv.h
--- a/drivers/gpu/drm/i915/i915_drv.h~drm-i915-wire-up-shrinkctl-nr_scanned
+++ a/drivers/gpu/drm/i915/i915_drv.h
@@ -3628,6 +3628,7 @@ i915_gem_object_create_internal(struct d
/* 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 -puN drivers/gpu/drm/i915/i915_gem.c~drm-i915-wire-up-shrinkctl-nr_scanned drivers/gpu/drm/i915/i915_gem.c
--- a/drivers/gpu/drm/i915/i915_gem.c~drm-i915-wire-up-shrinkctl-nr_scanned
+++ a/drivers/gpu/drm/i915/i915_gem.c
@@ -2408,7 +2408,7 @@ rebuild_st:
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
@@ -5012,7 +5012,7 @@ int i915_gem_freeze_late(struct drm_i915
* 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);
mutex_lock(&dev_priv->drm.struct_mutex);
diff -puN drivers/gpu/drm/i915/i915_gem_gtt.c~drm-i915-wire-up-shrinkctl-nr_scanned drivers/gpu/drm/i915/i915_gem_gtt.c
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c~drm-i915-wire-up-shrinkctl-nr_scanned
+++ a/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -2061,7 +2061,7 @@ int i915_gem_gtt_prepare_pages(struct dr
*/
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 -puN drivers/gpu/drm/i915/i915_gem_shrinker.c~drm-i915-wire-up-shrinkctl-nr_scanned drivers/gpu/drm/i915/i915_gem_shrinker.c
--- a/drivers/gpu/drm/i915/i915_gem_shrinker.c~drm-i915-wire-up-shrinkctl-nr_scanned
+++ a/drivers/gpu/drm/i915/i915_gem_shrinker.c
@@ -136,6 +136,7 @@ static bool unsafe_drop_pages(struct drm
* 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
@@ -158,7 +159,9 @@ static bool unsafe_drop_pages(struct drm
*/
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;
@@ -169,6 +172,7 @@ i915_gem_shrink(struct drm_i915_private
{ NULL, 0 },
}, *phase;
unsigned long count = 0;
+ unsigned long scanned = 0;
bool unlock;
if (!shrinker_lock(dev_priv, &unlock))
@@ -249,6 +253,7 @@ i915_gem_shrink(struct drm_i915_private
count += obj->base.size >> PAGE_SHIFT;
}
mutex_unlock(&obj->mm.lock);
+ scanned += obj->base.size >> PAGE_SHIFT;
}
}
list_splice_tail(&still_in_list, phase->list);
@@ -261,6 +266,8 @@ i915_gem_shrink(struct drm_i915_private
shrinker_unlock(dev_priv, unlock);
+ if (nr_scanned)
+ *nr_scanned += scanned;
return count;
}
@@ -283,7 +290,7 @@ unsigned long i915_gem_shrink_all(struct
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);
@@ -329,23 +336,28 @@ i915_gem_shrinker_scan(struct shrinker *
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);
@@ -354,7 +366,7 @@ i915_gem_shrinker_scan(struct shrinker *
shrinker_unlock(dev_priv, unlock);
- return freed;
+ return sc->nr_scanned ? freed : SHRINK_STOP;
}
static bool
@@ -453,7 +465,7 @@ i915_gem_shrinker_vmap(struct notifier_b
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 |
_
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