In commit 5ba32c7be8 ("drm/i915/execlists: Always force a context
reload when rewinding RING_TAIL"), we placed the check for rewinding a
context on actually submitting the next request in that context. This
was so that we only had to check once, and could do so with precision
avoiding as many forced restores as possible. For example, to ensure
that we can resubmit the same request a couple of times, we include a
small wa_tail such that on the next submission, the ring->tail will
appear to move forwards when resubmitting the same request. This is very
common as it will happen for every lite-restore to fill the second port
after a context switch.
However, intel_ring_direction() is limited in precision to movements of
upto half the ring size. The consequence being that if we tried to
unwind many requests, we could exceed half the ring and flip the sense
of the direction, so missing a force restore. As no request can be
greater than half the ring (i.e. 2048 bytes in the smallest case), we
can check for rollback incrementally. As we check against the tail that
would be submitted, we do not lose any sensitivity and allow lite
restores for the simple case. We still need to double check upon
submitting the context, to allow for multiple preemptions and
resubmissions.
Fixes: 5ba32c7be8 ("drm/i915/execlists: Always force a context reload when rewinding RING_TAIL")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: <stable@vger.kernel.org> # v5.4+
Reviewed-by: Bruce Chang <yu.bruce.chang@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200609151723.12971-1-chris@chris-wilson.co.uk
We should be able to skip restoring LOCAL (user) binds within the GGTT on
resume and let them be restored upon demand. However, our consistency
checks demand that the bind flags match the node state, and we cannot
simply clear the flags, we need to evict as well. For now, make sure we
restore the bind flags exactly upon resume.
Fixes: 0109a16ef3 ("drm/i915/gt: Clear LOCAL_BIND from shared GGTT on resume")
Fixes: bf0840cdb3 ("drm/i915/gt: Stop cross-polluting PIN_GLOBAL with PIN_USER with no-ppgtt")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200528150452.7880-1-chris@chris-wilson.co.uk
We have a I915_REQUEST_NOPREEMPT flag that we set when we must prevent
the HW from preempting during the course of this request. We need to
honour this flag and protect the HW even if we have a heartbeat request,
or other maximum priority barrier, pending. As such, restrict the
timeslicing check to avoid preempting into the topmost priority band,
leaving the unpreemptable requests in blissful peace running
uninterrupted on the HW.
v2: Set the I915_PRIORITY_BARRIER to be less than
I915_PRIORITY_UNPREEMPTABLE so that we never submit a request
(heartbeat or barrier) that can legitimately preempt the current
non-premptable request.
Fixes: 2a98f4e65b ("drm/i915: add infrastructure to hold off preemption on a request")
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/20200527162418.24755-1-chris@chris-wilson.co.uk
gcc-9 gets confused by the code flow in check_dirty_whitelist:
drivers/gpu/drm/i915/gt/selftest_workarounds.c: In function 'check_dirty_whitelist':
drivers/gpu/drm/i915/gt/selftest_workarounds.c:492:17: error: 'rsvd' may be used uninitialized in this function [-Werror=maybe-uninitialized]
I could not figure out a good way to do this in a way that gcc
understands better, so initialize the variable to zero, as last
resort.
Fixes: aee20aaed8 ("drm/i915: Implement read-only support in whitelist selftest")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20200527140526.1458215-2-arnd@arndb.de
We only restore GLOBAL binds upon resume as we expect these to be pinned
for use by HW, whereas the LOCAL binds can be recreated on demand once
userspace is resumed. For the LOCAL bind to be recreated in the global
GTT (for old systems without ppgtt), we need to clear its presence flag
on deciding not to restore the mapping upon resume.
Fixes: bf0840cdb3 ("drm/i915/gt: Stop cross-polluting PIN_GLOBAL with PIN_USER with no-ppgtt")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200526150739.26147-1-chris@chris-wilson.co.uk
Since the worker may rearm, we currently are only guaranteed to flush
the work if we cancel the timer. If the work was running at the time we
try and cancel it, we will wait for it to complete, but it may leave
items in the pool and requeue the work. If we rearrange the immediate
discard of the pool then cancel the work, we know that the work cannot
rearm and so our flush will be final.
<0> [314.146044] i915_mod-1321 2.... 299799443us : intel_gt_fini_buffer_pool: intel_gt_fini_buffer_pool:227 GEM_BUG_ON(!list_empty(&pool->cache_list[n]))
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/1920
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200525141957.3061-1-chris@chris-wilson.co.uk
If we decide to timeslice out the current virtual request, we will
unsubmit it while it is still busy (ve->context.inflight == sibling[0]).
If the virtual tasklet and then the other sibling tasklets run before we
completely schedule out the active virtual request for the preemption,
those other tasklets will see that the virtul request is still inflight
on sibling[0] and leave it be. Therefore when we finally schedule-out
the virtual request and if we see that we have passed it back to the
virtual engine, reschedule the virtual tasklet so that it may be
resubmitted on any of the siblings.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200519132046.22443-2-chris@chris-wilson.co.uk
The second try at staging the transfer of the breadcrumb. In part one,
we realised we could not simply move to the second engine as we were
only holding the breadcrumb lock on the first. So in commit 6c81e21a47
("drm/i915/gt: Stage the transfer of the virtual breadcrumb"), we
removed it from the first engine and marked up this request to reattach
the signaling on the new engine. However, this failed to take into
account that we only attach the breadcrumb if the new request is added
at the start of the queue, which if we are transferring, it is because
we know there to be a request to be signaled (and hence we would not be
attached).
In this attempt, we try to transfer the completed requests to the
irq_worker on its rq->engine->breadcrumbs. This preserves the coupling
between the rq and its breadcrumbs, so that
i915_request_cancel_breadcrumb() does not attempt to manipulate the list
under the wrong lock.
v2: Code sharing is fun.
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/1862
Fixes: 6c81e21a47 ("drm/i915/gt: Stage the transfer of the virtual breadcrumb")
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/20200513074809.18194-1-chris@chris-wilson.co.uk
By providing the default values configured into the kernel via sysfs, it
is much more convenient for userspace to restore those sane defaults, or
at least know what are considered good baseline. This is useful, for
example, to cleanup after any failed userspace prior to commencing new
jobs.
/sys/class/drm/card0/engine/rcs0/
├── capabilities
├── class
├── .defaults
│ ├── heartbeat_interval_ms
│ ├── max_busywait_duration_ns
│ ├── preempt_timeout_ms
│ ├── stop_timeout_ms
│ └── timeslice_duration_ms
├── heartbeat_interval_ms
├── instance
├── known_capabilities
├── max_busywait_duration_ns
├── mmio_base
├── name
├── preempt_timeout_ms
├── stop_timeout_ms
└── timeslice_duration_ms
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Maciej Patelczyk <maciej.patelczyk@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200514062905.28668-1-chris@chris-wilson.co.uk
Now that we have fast timeslicing on semaphores, we no longer need to
prioritise none-semaphore work as we will yield any work blocked on a
semaphore to the next in the queue. Previously with no timeslicing,
blocking on the semaphore caused extremely bad scheduling with multiple
clients utilising multiple rings. Now, there is no impact and we can
remove the complication.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200513173504.28322-1-chris@chris-wilson.co.uk
The initial-breadcrumb is used to mark the end of the awaiting and the
beginning of the user payload. We verify that we do not start the user
payload before all signaler are completed, checking our semaphore setup
by looking for the initial breadcrumb being written too early. We also
want to ensure that we do not add semaphore waits after we have already
closed the semaphore section, an issue for later deferred waits.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200513165937.9508-2-chris@chris-wilson.co.uk
