Skip to content

K
Kernel

openeuler / Kernel
1 年多 前同步成功

通知 8
Star 0
Fork 0
K
Kernel
切换分支/标签
  1. 06 3月, 2019 1 次提交
  3. 05 3月, 2019 1 次提交
  5. 26 2月, 2019 2 次提交
  7. 19 2月, 2019 1 次提交
    • C
      drm/i915: Use time based guilty context banning · 7f4127c4
      由 Chris Wilson 提交于 
      Currently, we accumulate each time a context hangs the GPU, offset
against the number of requests it submits, and if that score exceeds a
certain threshold, we ban that context from submitting any more requests
(cancelling any work in flight). In contrast, we use a simple timer on
the file, that if we see more than a 9 hangs faster than 60s apart in
total across all of its contexts, we will ban the client from creating
any more contexts. This leads to a confusing situation where the file
may be banned before the context, so lets use a simple timer scheme for
each.

If the context submits 3 hanging requests within a 120s period, declare
it forbidden to ever send more requests.

This has the advantage of not being easy to repair by simply sending
empty requests, but has the disadvantage that if the context is idle
then it is forgiven. However, if the context is idle, it is not
disrupting the system, but a hog can evade the request counting and
cause much more severe disruption to the system.

Updating ban_score from request retirement is dubious as the retirement
is purposely not in sync with request submission (i.e. we try and batch
retirement to reduce overhead and avoid latency on submission), which
leads to surprising situations where we can forgive a hang immediately
due to a backlog of requests from before the hang being retired
afterwards.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190219122215.8941-2-chris@chris-wilson.co.uk
      7f4127c4
  9. 06 2月, 2019 1 次提交
  11. 30 1月, 2019 2 次提交
    • C
      drm/i915: Drop fake breadcrumb irq · 789659f4
      由 Chris Wilson 提交于 
      Missed breadcrumb detection is defunct due to the tight coupling with
dma_fence signaling and the myriad ways we may signal fences from
everywhere but from an interrupt, i.e. we frequently signal a fence
before we even see its interrupt. This means that even if we miss an
interrupt for a fence, it still is signaled before our breadcrumb
hangcheck fires, so simplify the breadcrumb hangchecking by moving it
into the GPU hangcheck and forgo fake interrupts.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190129205230.19056-3-chris@chris-wilson.co.uk
      789659f4
    • C
      drm/i915: Replace global breadcrumbs with per-context interrupt tracking · 52c0fdb2
      由 Chris Wilson 提交于 
      A few years ago, see commit 688e6c72 ("drm/i915: Slaughter the
thundering i915_wait_request herd"), the issue of handling multiple
clients waiting in parallel was brought to our attention. The
requirement was that every client should be woken immediately upon its
request being signaled, without incurring any cpu overhead.

To handle certain fragility of our hw meant that we could not do a
simple check inside the irq handler (some generations required almost
unbounded delays before we could be sure of seqno coherency) and so
request completion checking required delegation.

Before commit 688e6c72, the solution was simple. Every client
waiting on a request would be woken on every interrupt and each would do
a heavyweight check to see if their request was complete. Commit
688e6c72 introduced an rbtree so that only the earliest waiter on
the global timeline would woken, and would wake the next and so on.
(Along with various complications to handle requests being reordered
along the global timeline, and also a requirement for kthread to provide
a delegate for fence signaling that had no process context.)

The global rbtree depends on knowing the execution timeline (and global
seqno). Without knowing that order, we must instead check all contexts
queued to the HW to see which may have advanced. We trim that list by
only checking queued contexts that are being waited on, but still we
keep a list of all active contexts and their active signalers that we
inspect from inside the irq handler. By moving the waiters onto the fence
signal list, we can combine the client wakeup with the dma_fence
signaling (a dramatic reduction in complexity, but does require the HW
being coherent, the seqno must be visible from the cpu before the
interrupt is raised - we keep a timer backup just in case).

Having previously fixed all the issues with irq-seqno serialisation (by
inserting delays onto the GPU after each request instead of random delays
on the CPU after each interrupt), we can rely on the seqno state to
perfom direct wakeups from the interrupt handler. This allows us to
preserve our single context switch behaviour of the current routine,
with the only downside that we lose the RT priority sorting of wakeups.
In general, direct wakeup latency of multiple clients is about the same
(about 10% better in most cases) with a reduction in total CPU time spent
in the waiter (about 20-50% depending on gen). Average herd behaviour is
improved, but at the cost of not delegating wakeups on task_prio.

v2: Capture fence signaling state for error state and add comments to
warm even the most cold of hearts.
v3: Check if the request is still active before busywaiting
v4: Reduce the amount of pointer misdirection with list_for_each_safe
and using a local i915_request variable inside the loops
v5: Add a missing pluralisation to a purely informative selftest message.

References: 688e6c72 ("drm/i915: Slaughter the thundering i915_wait_request herd")
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190129205230.19056-2-chris@chris-wilson.co.uk
      52c0fdb2
  13. 29 1月, 2019 1 次提交
    • C
      drm/i915: Stop tracking MRU activity on VMA · 499197dc
      由 Chris Wilson 提交于 
      Our goal is to remove struct_mutex and replace it with fine grained
locking. One of the thorny issues is our eviction logic for reclaiming
space for an execbuffer (or GTT mmaping, among a few other examples).
While eviction itself is easy to move under a per-VM mutex, performing
the activity tracking is less agreeable. One solution is not to do any
MRU tracking and do a simple coarse evaluation during eviction of
active/inactive, with a loose temporal ordering of last
insertion/evaluation. That keeps all the locking constrained to when we
are manipulating the VM itself, neatly avoiding the tricky handling of
possible recursive locking during execbuf and elsewhere.

Note that discarding the MRU (currently implemented as a pair of lists,
to avoid scanning the active list for a NONBLOCKING search) is unlikely
to impact upon our efficiency to reclaim VM space (where we think a LRU
model is best) as our current strategy is to use random idle replacement
first before doing a search, and over time the use of softpinned 48b
per-ppGTT is growing (thereby eliminating any need to perform any eviction
searches, in theory at least) with the remaining users being found on
much older devices (gen2-gen6).

v2: Changelog and commentary rewritten to elaborate on the duality of a
single list being both an inactive and active list.
v3: Consolidate bool parameters into a single set of flags; don't
comment on the duality of a single variable being a multiplicity of
bits.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190128102356.15037-1-chris@chris-wilson.co.uk
      499197dc
  15. 25 1月, 2019 1 次提交
  17. 17 1月, 2019 1 次提交
  19. 10 1月, 2019 2 次提交
  21. 03 1月, 2019 1 次提交
  23. 02 1月, 2019 1 次提交
  25. 31 12月, 2018 2 次提交
  27. 13 12月, 2018 2 次提交
  29. 12 12月, 2018 1 次提交
  31. 07 12月, 2018 1 次提交
  33. 04 12月, 2018 1 次提交
  35. 23 11月, 2018 1 次提交
    • C
      drm/i915: Cache the error string · 0e39037b
      由 Chris Wilson 提交于 
      Currently, we convert the error state into a string every time we read
from sysfs (and sysfs reads in page size (4KiB) chunks). We do try to
window the string and only capture the portion that is being read, but
that means that we must always convert up to the window to find the
start. For a very large error state bordering on EXEC_OBJECT_CAPTURE
abuse, this is noticeable as it degrades to O(N^2)!

As we do not have a convenient hook for sysfs open(), and we would like
to keep the lazy conversion into a string, do the conversion of the
whole string on the first read and keep the string until the error state
is freed.

v2: Don't double advance simple_read_from_buffer
v3: Due to extreme pain of lack of vrealloc, use a scatterlist
v4: Keep the forward iterator loosely cached
v5: Stylistic improvements to reduce patch size
Reported-by: NJason Ekstrand <jason@jlekstrand.net>
Testcase: igt/gem_exec_capture/many*
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181123132325.26541-1-chris@chris-wilson.co.uk
      0e39037b
  37. 22 11月, 2018 1 次提交
  39. 20 11月, 2018 2 次提交
  41. 03 10月, 2018 3 次提交
  43. 27 9月, 2018 1 次提交
  45. 15 9月, 2018 1 次提交
  47. 30 7月, 2018 1 次提交
  49. 07 7月, 2018 1 次提交
  51. 08 6月, 2018 1 次提交
  53. 06 6月, 2018 2 次提交
  55. 18 5月, 2018 3 次提交
  57. 03 5月, 2018 1 次提交