From d9948a10b90201d1aa91e5a96daa09f40f7bb282 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Thu, 28 Feb 2019 10:20:35 +0000 Subject: [PATCH] drm/i915: Remove second level open-coded rcu work 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 Cc: Tvrtko Ursulin Reviewed-by: Tvrtko Ursulin Link: https://patchwork.freedesktop.org/patch/msgid/20190228102035.5857-3-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_debugfs.c | 6 +- drivers/gpu/drm/i915/i915_drv.h | 6 -- drivers/gpu/drm/i915/i915_gem.c | 88 ++--------------------------- 3 files changed, 6 insertions(+), 94 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c index 545091a5180b..298371aad445 100644 --- a/drivers/gpu/drm/i915/i915_debugfs.c +++ b/drivers/gpu/drm/i915/i915_debugfs.c @@ -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", diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 35516089a3ff..453af7438e67 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -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 diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 901399d9e25b..a1ad5e137a97 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -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) -- 2.30.2