This essentially reverts
commit
84a1074920523430f9dc30ff907f4801b4820072
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Wed Jan 24 11:36:08 2018 +0000
drm/i915: Shrink the GEM kmem_caches upon idling
mm/vmscan.c:do_shrink_slab() is a thing, if there's an issue with it
then we need to fix that there, not hand-roll our own slab shrinking
code in i915.
Also when this was added there was only one other caller of
kmem_cache_shrink (added 2005 to the acpi code). Now there's a 2nd one
outside of i915 code in a kunit test, which seems legit since that
wants to very carefully control what's in the kmem_cache. This out of
a total of over 500 calls to kmem_cache_create. This alone should have
been warning sign enough that we're doing something silly.
Noticed while reviewing a patch set from Jason to fix up some issues
in our i915_init() and i915_exit() module load/cleanup code. Now that
i915_globals.c isn't any different than normal init/exit functions, we
should convert them over to one unified table and remove
i915_globals.[hc] entirely.
v2: Improve commit message (Jason)
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Cc: David Airlie <airlied@linux.ie>
Cc: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210721183229.4136488-1-daniel.vetter@ffwll.ch
#include "selftests/i915_gem_context.c"
#endif
-static void i915_global_gem_context_shrink(void)
-{
- kmem_cache_shrink(global.slab_luts);
-}
-
static void i915_global_gem_context_exit(void)
{
kmem_cache_destroy(global.slab_luts);
}
static struct i915_global_gem_context global = { {
- .shrink = i915_global_gem_context_shrink,
.exit = i915_global_gem_context_exit,
} };
INIT_WORK(&i915->mm.free_work, __i915_gem_free_work);
}
-static void i915_global_objects_shrink(void)
-{
- kmem_cache_shrink(global.slab_objects);
-}
-
static void i915_global_objects_exit(void)
{
kmem_cache_destroy(global.slab_objects);
}
static struct i915_global_object global = { {
- .shrink = i915_global_objects_shrink,
.exit = i915_global_objects_exit,
} };
i915_active_fini(&ce->active);
}
-static void i915_global_context_shrink(void)
-{
- kmem_cache_shrink(global.slab_ce);
-}
-
static void i915_global_context_exit(void)
{
kmem_cache_destroy(global.slab_ce);
}
static struct i915_global_context global = { {
- .shrink = i915_global_context_shrink,
.exit = i915_global_context_exit,
} };
GT_TRACE(gt, "\n");
- i915_globals_unpark();
-
/*
* It seems that the DMC likes to transition between the DC states a lot
* when there are no connected displays (no active power domains) during
GEM_BUG_ON(!wakeref);
intel_display_power_put_async(i915, POWER_DOMAIN_GT_IRQ, wakeref);
- i915_globals_park();
-
return 0;
}
#include "selftests/i915_active.c"
#endif
-static void i915_global_active_shrink(void)
-{
- kmem_cache_shrink(global.slab_cache);
-}
-
static void i915_global_active_exit(void)
{
kmem_cache_destroy(global.slab_cache);
}
static struct i915_global_active global = { {
- .shrink = i915_global_active_shrink,
.exit = i915_global_active_exit,
} };
static LIST_HEAD(globals);
-static atomic_t active;
-static atomic_t epoch;
-static struct park_work {
- struct delayed_work work;
- struct rcu_head rcu;
- unsigned long flags;
-#define PENDING 0
- int epoch;
-} park;
-
-static void i915_globals_shrink(void)
-{
- struct i915_global *global;
-
- /*
- * kmem_cache_shrink() discards empty slabs and reorders partially
- * filled slabs to prioritise allocating from the mostly full slabs,
- * with the aim of reducing fragmentation.
- */
- list_for_each_entry(global, &globals, link)
- global->shrink();
-}
-
-static void __i915_globals_grace(struct rcu_head *rcu)
-{
- /* Ratelimit parking as shrinking is quite slow */
- schedule_delayed_work(&park.work, round_jiffies_up_relative(2 * HZ));
-}
-
-static void __i915_globals_queue_rcu(void)
-{
- park.epoch = atomic_inc_return(&epoch);
- if (!atomic_read(&active)) {
- init_rcu_head(&park.rcu);
- call_rcu(&park.rcu, __i915_globals_grace);
- }
-}
-
-static void __i915_globals_park(struct work_struct *work)
-{
- destroy_rcu_head(&park.rcu);
-
- /* Confirm nothing woke up in the last grace period */
- if (park.epoch != atomic_read(&epoch)) {
- __i915_globals_queue_rcu();
- return;
- }
-
- clear_bit(PENDING, &park.flags);
- i915_globals_shrink();
-}
-
void __init i915_global_register(struct i915_global *global)
{
- GEM_BUG_ON(!global->shrink);
GEM_BUG_ON(!global->exit);
list_add_tail(&global->link, &globals);
}
}
- INIT_DELAYED_WORK(&park.work, __i915_globals_park);
return 0;
}
-void i915_globals_park(void)
-{
- /*
- * Defer shrinking the global slab caches (and other work) until
- * after a RCU grace period has completed with no activity. This
- * is to try and reduce the latency impact on the consumers caused
- * by us shrinking the caches the same time as they are trying to
- * allocate, with the assumption being that if we idle long enough
- * for an RCU grace period to elapse since the last use, it is likely
- * to be longer until we need the caches again.
- */
- if (!atomic_dec_and_test(&active))
- return;
-
- /* Queue cleanup after the next RCU grace period has freed slabs */
- if (!test_and_set_bit(PENDING, &park.flags))
- __i915_globals_queue_rcu();
-}
-
-void i915_globals_unpark(void)
-{
- atomic_inc(&epoch);
- atomic_inc(&active);
-}
-
-static void __exit __i915_globals_flush(void)
-{
- atomic_inc(&active); /* skip shrinking */
-
- rcu_barrier(); /* wait for the work to be queued */
- flush_delayed_work(&park.work);
-
- atomic_dec(&active);
-}
-
void __exit i915_globals_exit(void)
{
- GEM_BUG_ON(atomic_read(&active));
-
- __i915_globals_flush();
__i915_globals_cleanup();
-
- /* And ensure that our DESTROY_BY_RCU slabs are truly destroyed */
- rcu_barrier();
}
struct i915_global {
struct list_head link;
- i915_global_func_t shrink;
i915_global_func_t exit;
};
void i915_global_register(struct i915_global *global);
int i915_globals_init(void);
-void i915_globals_park(void);
-void i915_globals_unpark(void);
void i915_globals_exit(void);
/* constructors */
#include "selftests/i915_request.c"
#endif
-static void i915_global_request_shrink(void)
-{
- kmem_cache_shrink(global.slab_execute_cbs);
- kmem_cache_shrink(global.slab_requests);
-}
-
static void i915_global_request_exit(void)
{
kmem_cache_destroy(global.slab_execute_cbs);
}
static struct i915_global_request global = { {
- .shrink = i915_global_request_shrink,
.exit = i915_global_request_exit,
} };
return sched_engine;
}
-static void i915_global_scheduler_shrink(void)
-{
- kmem_cache_shrink(global.slab_dependencies);
- kmem_cache_shrink(global.slab_priorities);
-}
-
static void i915_global_scheduler_exit(void)
{
kmem_cache_destroy(global.slab_dependencies);
}
static struct i915_global_scheduler global = { {
- .shrink = i915_global_scheduler_shrink,
.exit = i915_global_scheduler_exit,
} };
#include "selftests/i915_vma.c"
#endif
-static void i915_global_vma_shrink(void)
-{
- kmem_cache_shrink(global.slab_vmas);
-}
-
static void i915_global_vma_exit(void)
{
kmem_cache_destroy(global.slab_vmas);
}
static struct i915_global_vma global = { {
- .shrink = i915_global_vma_shrink,
.exit = i915_global_vma_exit,
} };
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