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drm/i915: Remove second level open-coded rcu work

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We currently use a worker queued from an rcu callback to determine when
a how grace period has elapsed while we remained idle. We use this idle
delay to infer that we will be idle for a while and this is a suitable
point at which we can trim our global memory caches.

Since we wrote that, this mechanism now exists as rcu_work, and having
converted the idle shrinkers over to using that, we can remove our own
variant.

v2: Say goodbye to gt.epoch as well.
v3: Remove the misplaced and redundant comment before parking globals

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190228102035.5857-3-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2019-02-28 10:20:35 +00:00
parent 13f1bfd3b3
commit d9948a10b9
3 changed files with 6 additions and 94 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/gpu/drm/i915/i915_debugfs.c
View File

@ -2655,8 +2655,7 @@ static int i915_runtime_pm_status(struct seq_file *m, void *unused)
seq_printf(m, "Runtime power status: %s\n",
enableddisabled(!dev_priv->power_domains.wakeref));
seq_printf(m, "GPU idle: %s (epoch %u)\n",
yesno(!dev_priv->gt.awake), dev_priv->gt.epoch);
seq_printf(m, "GPU idle: %s\n", yesno(!dev_priv->gt.awake));
seq_printf(m, "IRQs disabled: %s\n",
yesno(!intel_irqs_enabled(dev_priv)));
#ifdef CONFIG_PM
@ -3092,8 +3091,7 @@ static int i915_engine_info(struct seq_file *m, void *unused)
wakeref = intel_runtime_pm_get(dev_priv);
seq_printf(m, "GT awake? %s (epoch %u)\n",
yesno(dev_priv->gt.awake), dev_priv->gt.epoch);
seq_printf(m, "GT awake? %s\n", yesno(dev_priv->gt.awake));
seq_printf(m, "Global active requests: %d\n",
dev_priv->gt.active_requests);
seq_printf(m, "CS timestamp frequency: %u kHz\n",

6
drivers/gpu/drm/i915/i915_drv.h
View File

@ -2005,12 +2005,6 @@ struct drm_i915_private {
*/
intel_wakeref_t awake;
/**
* The number of times we have woken up.
*/
unsigned int epoch;
#define I915_EPOCH_INVALID 0
/**
* We leave the user IRQ off as much as possible,
* but this means that requests will finish and never

88
drivers/gpu/drm/i915/i915_gem.c
View File

@ -101,7 +101,7 @@ static void i915_gem_info_remove_obj(struct drm_i915_private *dev_priv,
spin_unlock(&dev_priv->mm.object_stat_lock);
}
static u32 __i915_gem_park(struct drm_i915_private *i915)
static void __i915_gem_park(struct drm_i915_private *i915)
{
intel_wakeref_t wakeref;
@ -112,9 +112,7 @@ static u32 __i915_gem_park(struct drm_i915_private *i915)
GEM_BUG_ON(!list_empty(&i915->gt.active_rings));
if (!i915->gt.awake)
return I915_EPOCH_INVALID;
GEM_BUG_ON(i915->gt.epoch == I915_EPOCH_INVALID);
return;
/*
* Be paranoid and flush a concurrent interrupt to make sure
@ -143,7 +141,7 @@ static u32 __i915_gem_park(struct drm_i915_private *i915)
intel_display_power_put(i915, POWER_DOMAIN_GT_IRQ, wakeref);
return i915->gt.epoch;
i915_globals_park();
}
void i915_gem_park(struct drm_i915_private *i915)
@ -185,9 +183,6 @@ void i915_gem_unpark(struct drm_i915_private *i915)
i915->gt.awake = intel_display_power_get(i915, POWER_DOMAIN_GT_IRQ);
GEM_BUG_ON(!i915->gt.awake);
if (unlikely(++i915->gt.epoch == 0)) /* keep 0 as invalid */
i915->gt.epoch = 1;
i915_globals_unpark();
intel_enable_gt_powersave(i915);
@ -2877,62 +2872,6 @@ i915_gem_retire_work_handler(struct work_struct *work)
round_jiffies_up_relative(HZ));
}
static void shrink_caches(struct drm_i915_private *i915)
{
/*
* 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.
*/
i915_globals_park();
}
struct sleep_rcu_work {
union {
struct rcu_head rcu;
struct work_struct work;
};
struct drm_i915_private *i915;
unsigned int epoch;
};
static inline bool
same_epoch(struct drm_i915_private *i915, unsigned int epoch)
{
/*
* There is a small chance that the epoch wrapped since we started
* sleeping. If we assume that epoch is at least a u32, then it will
* take at least 2^32 * 100ms for it to wrap, or about 326 years.
*/
return epoch == READ_ONCE(i915->gt.epoch);
}
static void __sleep_work(struct work_struct *work)
{
struct sleep_rcu_work *s = container_of(work, typeof(*s), work);
struct drm_i915_private *i915 = s->i915;
unsigned int epoch = s->epoch;
kfree(s);
if (same_epoch(i915, epoch))
shrink_caches(i915);
}
static void __sleep_rcu(struct rcu_head *rcu)
{
struct sleep_rcu_work *s = container_of(rcu, typeof(*s), rcu);
struct drm_i915_private *i915 = s->i915;
destroy_rcu_head(&s->rcu);
if (same_epoch(i915, s->epoch)) {
INIT_WORK(&s->work, __sleep_work);
queue_work(i915->wq, &s->work);
} else {
kfree(s);
}
}
static inline bool
new_requests_since_last_retire(const struct drm_i915_private *i915)
{
@ -2961,7 +2900,6 @@ i915_gem_idle_work_handler(struct work_struct *work)
{
struct drm_i915_private *dev_priv =
container_of(work, typeof(*dev_priv), gt.idle_work.work);
unsigned int epoch = I915_EPOCH_INVALID;
bool rearm_hangcheck;
if (!READ_ONCE(dev_priv->gt.awake))
@ -3016,7 +2954,7 @@ i915_gem_idle_work_handler(struct work_struct *work)
if (new_requests_since_last_retire(dev_priv))
goto out_unlock;
epoch = __i915_gem_park(dev_priv);
__i915_gem_park(dev_priv);
assert_kernel_context_is_current(dev_priv);
@ -3029,24 +2967,6 @@ out_rearm:
GEM_BUG_ON(!dev_priv->gt.awake);
i915_queue_hangcheck(dev_priv);
}
/*
* When we are idle, it is an opportune time to reap our caches.
* However, we have many objects that utilise RCU and the ordered
* i915->wq that this work is executing on. To try and flush any
* pending frees now we are idle, we first wait for an RCU grace
* period, and then queue a task (that will run last on the wq) to
* shrink and re-optimize the caches.
*/
if (same_epoch(dev_priv, epoch)) {
struct sleep_rcu_work *s = kmalloc(sizeof(*s), GFP_KERNEL);
if (s) {
init_rcu_head(&s->rcu);
s->i915 = dev_priv;
s->epoch = epoch;
call_rcu(&s->rcu, __sleep_rcu);
}
}
}
void i915_gem_close_object(struct drm_gem_object *gem, struct drm_file *file)