[Intel-gfx] [PATCH v3 4/6] drm/i915: Request watchdog infrastructure
Tvrtko Ursulin
tvrtko.ursulin at linux.intel.com
Tue Mar 23 11:09:42 UTC 2021
On 23/03/2021 10:54, Matthew Auld wrote:
> On Mon, 22 Mar 2021 at 13:29, Tvrtko Ursulin
> <tvrtko.ursulin at linux.intel.com> wrote:
>>
>> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
>>
>> Prepares the plumbing for setting request/fence expiration time. All code
>> is put in place but is never activeted due yet missing ability to actually
>
> activated
>
>> configure the timer.
>>
>> Outline of the basic operation:
>>
>> A timer is started when request is ready for execution. If the request
>> completes (retires) before the timer fires, timer is cancelled and nothing
>> further happens.
>>
>> If the timer fires request is added to a lockless list and worker queued.
>> Purpose of this is twofold: a) It allows request cancellation from a more
>> friendly context and b) coalesces multiple expirations into a single event
>> of consuming the list.
>>
>> Worker locklessly consumes the list of expired requests and cancels them
>> all using previous added i915_request_cancel().
>>
>> Associated timeout value is stored in rq->context.watchdog.timeout_us.
>>
>> v2:
>> * Log expiration.
>>
>> v3:
>> * Include more information about user timeline in the log message.
>>
>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
>> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
>> ---
>> drivers/gpu/drm/i915/gt/intel_context_types.h | 4 ++
>> .../drm/i915/gt/intel_execlists_submission.h | 2 +
>> drivers/gpu/drm/i915/gt/intel_gt.c | 3 +
>> drivers/gpu/drm/i915/gt/intel_gt.h | 2 +
>> drivers/gpu/drm/i915/gt/intel_gt_requests.c | 28 ++++++++++
>> drivers/gpu/drm/i915/gt/intel_gt_types.h | 7 +++
>> drivers/gpu/drm/i915/i915_request.c | 56 +++++++++++++++++++
>> drivers/gpu/drm/i915/i915_request.h | 8 +++
>> 8 files changed, 110 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
>> index 0ea18c9e2aca..65a5730a4f5b 100644
>> --- a/drivers/gpu/drm/i915/gt/intel_context_types.h
>> +++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
>> @@ -99,6 +99,10 @@ struct intel_context {
>> #define CONTEXT_FORCE_SINGLE_SUBMISSION 7
>> #define CONTEXT_NOPREEMPT 8
>>
>> + struct {
>> + u64 timeout_us;
>> + } watchdog;
>> +
>> u32 *lrc_reg_state;
>> union {
>> struct {
>> diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.h b/drivers/gpu/drm/i915/gt/intel_execlists_submission.h
>> index f7bd3fccfee8..4ca9b475e252 100644
>> --- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.h
>> +++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.h
>> @@ -6,6 +6,7 @@
>> #ifndef __INTEL_EXECLISTS_SUBMISSION_H__
>> #define __INTEL_EXECLISTS_SUBMISSION_H__
>>
>> +#include <linux/llist.h>
>> #include <linux/types.h>
>>
>> struct drm_printer;
>> @@ -13,6 +14,7 @@ struct drm_printer;
>> struct i915_request;
>> struct intel_context;
>> struct intel_engine_cs;
>> +struct intel_gt;
>>
>> enum {
>> INTEL_CONTEXT_SCHEDULE_IN = 0,
>> diff --git a/drivers/gpu/drm/i915/gt/intel_gt.c b/drivers/gpu/drm/i915/gt/intel_gt.c
>> index ca76f93bc03d..8d77dcbad059 100644
>> --- a/drivers/gpu/drm/i915/gt/intel_gt.c
>> +++ b/drivers/gpu/drm/i915/gt/intel_gt.c
>> @@ -31,6 +31,9 @@ void intel_gt_init_early(struct intel_gt *gt, struct drm_i915_private *i915)
>> INIT_LIST_HEAD(>->closed_vma);
>> spin_lock_init(>->closed_lock);
>>
>> + init_llist_head(>->watchdog.list);
>> + INIT_WORK(>->watchdog.work, intel_gt_watchdog_work);
>> +
>> intel_gt_init_buffer_pool(gt);
>> intel_gt_init_reset(gt);
>> intel_gt_init_requests(gt);
>> diff --git a/drivers/gpu/drm/i915/gt/intel_gt.h b/drivers/gpu/drm/i915/gt/intel_gt.h
>> index a17bd8b3195f..7ec395cace69 100644
>> --- a/drivers/gpu/drm/i915/gt/intel_gt.h
>> +++ b/drivers/gpu/drm/i915/gt/intel_gt.h
>> @@ -78,4 +78,6 @@ static inline bool intel_gt_is_wedged(const struct intel_gt *gt)
>> void intel_gt_info_print(const struct intel_gt_info *info,
>> struct drm_printer *p);
>>
>> +void intel_gt_watchdog_work(struct work_struct *work);
>> +
>> #endif /* __INTEL_GT_H__ */
>> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_requests.c b/drivers/gpu/drm/i915/gt/intel_gt_requests.c
>> index 36ec97f79174..fbfd19b2e5f2 100644
>> --- a/drivers/gpu/drm/i915/gt/intel_gt_requests.c
>> +++ b/drivers/gpu/drm/i915/gt/intel_gt_requests.c
>> @@ -8,6 +8,7 @@
>> #include "i915_drv.h" /* for_each_engine() */
>> #include "i915_request.h"
>> #include "intel_engine_heartbeat.h"
>> +#include "intel_execlists_submission.h"
>> #include "intel_gt.h"
>> #include "intel_gt_pm.h"
>> #include "intel_gt_requests.h"
>> @@ -242,4 +243,31 @@ void intel_gt_fini_requests(struct intel_gt *gt)
>> {
>> /* Wait until the work is marked as finished before unloading! */
>> cancel_delayed_work_sync(>->requests.retire_work);
>> +
>> + flush_work(>->watchdog.work);
>> +}
>> +
>> +void intel_gt_watchdog_work(struct work_struct *work)
>> +{
>> + struct intel_gt *gt =
>> + container_of(work, typeof(*gt), watchdog.work);
>> + struct i915_request *rq, *rn;
>> + struct llist_node *first;
>> +
>> + first = llist_del_all(>->watchdog.list);
>> + if (!first)
>> + return;
>> +
>> + llist_for_each_entry_safe(rq, rn, first, watchdog.link) {
>> + if (!i915_request_completed(rq)) {
>> + struct dma_fence *f = &rq->fence;
>> +
>> + pr_notice("Fence expiration time out i915-%s:%s:%llx!\n",
>> + f->ops->get_driver_name(f),
>> + f->ops->get_timeline_name(f),
>> + f->seqno);
>> + i915_request_cancel(rq, -EINTR);
>> + }
>> + i915_request_put(rq);
>> + }
>> }
>> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_types.h b/drivers/gpu/drm/i915/gt/intel_gt_types.h
>> index 626af37c7790..d70ebcc6f19f 100644
>> --- a/drivers/gpu/drm/i915/gt/intel_gt_types.h
>> +++ b/drivers/gpu/drm/i915/gt/intel_gt_types.h
>> @@ -8,10 +8,12 @@
>>
>> #include <linux/ktime.h>
>> #include <linux/list.h>
>> +#include <linux/llist.h>
>> #include <linux/mutex.h>
>> #include <linux/notifier.h>
>> #include <linux/spinlock.h>
>> #include <linux/types.h>
>> +#include <linux/workqueue.h>
>>
>> #include "uc/intel_uc.h"
>>
>> @@ -62,6 +64,11 @@ struct intel_gt {
>> struct delayed_work retire_work;
>> } requests;
>>
>> + struct {
>> + struct llist_head list;
>> + struct work_struct work;
>> + } watchdog;
>> +
>> struct intel_wakeref wakeref;
>> atomic_t user_wakeref;
>>
>> diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
>> index b4511ac05e9a..9dd5e588b0a4 100644
>> --- a/drivers/gpu/drm/i915/i915_request.c
>> +++ b/drivers/gpu/drm/i915/i915_request.c
>> @@ -277,6 +277,57 @@ static void remove_from_engine(struct i915_request *rq)
>> __notify_execute_cb_imm(rq);
>> }
>>
>> +static void __rq_init_watchdog(struct i915_request *rq)
>> +{
>> + rq->watchdog.timer.function = NULL;
>> +}
>> +
>> +static enum hrtimer_restart __rq_watchdog_expired(struct hrtimer *hrtimer)
>> +{
>> + struct i915_request *rq =
>> + container_of(hrtimer, struct i915_request, watchdog.timer);
>> + struct intel_gt *gt = rq->engine->gt;
>> +
>> + if (!i915_request_completed(rq)) {
>> + if (llist_add(&rq->watchdog.link, >->watchdog.list))
>> + schedule_work(>->watchdog.work);
>> + } else {
>> + i915_request_put(rq);
>> + }
>> +
>> + return HRTIMER_NORESTART;
>> +}
>> +
>> +static void __rq_arm_watchdog(struct i915_request *rq)
>> +{
>> + struct i915_request_watchdog *wdg = &rq->watchdog;
>> + struct intel_context *ce = rq->context;
>> +
>> + if (!ce->watchdog.timeout_us)
>> + return;
>> +
>> + hrtimer_init(&wdg->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
>> + wdg->timer.function = __rq_watchdog_expired;
>> + hrtimer_start_range_ns(&wdg->timer,
>> + ns_to_ktime(ce->watchdog.timeout_us *
>> + NSEC_PER_USEC),
>> + /*
>> + * FIXME check if it gives the "not sooner"
>> + * guarantee or slack is both ways
>> + */
>
> It looks like the slack/fuzziness just delays the timer, in case it
> can coalesce multiple timer events. So shouldn't be sooner I think?
I couldn't quickly figure it out when I looked at the implementation so
I left this comment. But it was only relevant at a time I thought we
would be exposing context param to allow userspace control. With the
only user being default expiry which is not sensitive to precision or
accuracy, I simply need to remove this comment.
>
>> + NSEC_PER_MSEC,
>
> Formatting.
Which part? I think indentation/alignment is correct.
>
> Reviewed-by: Matthew Auld <matthew.auld at intel.com>
>
Thanks,
Tvrtko
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