- 05 Aug, 2016 21 commits
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Chris Wilson authored
With all callers now not playing tricks with dropping the struct_mutex between waiting and retiring, we can assert that the request is ready to be retired. Signed-off-by:
Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by:
Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1470388464-28458-19-git-send-email-chris@chris-wilson.co.uk
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Chris Wilson authored
In the previous commit, we moved the obj->tiling_mode out of a bitfield and into its own integer so that we could safely use READ_ONCE(). Let us now repair some of that damage by sharing the tiling_mode with its companion, the fence stride. v2: New magic Signed-off-by:
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Chris Wilson authored
Through the GTT interface to the fence registers, we can only handle linear, X and Y tiling. The more esoteric tiling patterns are ignored. Document that the tiling ABI only supports upto Y tiling, and reject any attempts to set a tiling mode other than NONE, X or Y. Signed-off-by:
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Chris Wilson authored
Since we are not concerned with userspace racing itself with set-tiling (the order is indeterminant even if we take a lock), then we can safely read back the single obj->tiling_mode and do the static lookup of swizzle mode without having to take a lock. get-tiling is reasonably frequent due to the back-channel passing around of tiling parameters in DRI2/DRI3. v2: Make tiling_mode a full unsigned int so that we can trivially use it with READ_ONCE(). Separating it out into manual control over the flags field was too noisy for a simple patch. Note that we could use the lower bits of obj->stride for the tiling mode. Signed-off-by:
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Chris Wilson authored
We don't need to incur the overhead of checking whether the object is pinned prior to changing its madvise. If the object is pinned, the madvise will not take effect until it is unpinned and so we cannot free the pages being pointed at by hardware. Marking a pinned object with allocated pages as DONTNEED will not trigger any undue warnings. The check is therefore superfluous, and by removing it we can remove a linear walk over all the vma the object has. Still despite it being an overzealous check, that error code is part of the current ABI and so we must proceed with caution. Signed-off-by:
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Chris Wilson authored
We only need to take the struct_mutex if the object is pinned to the display engine and so requires checking for clflush. (The race with userspace pinning the object to a framebuffer is irrelevant.) v2: Use access once for compiler hints (or not as it is a bitfield) v3: READ_ONCE, obj->pin_display is not a bitfield anymore v4: Don't be creative with goto. Signed-off-by:
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Chris Wilson authored
By applying the same logic as for wait-ioctl, we can query whether a request has completed without holding struct_mutex. The biggest impact system-wide is removing the flush_active and the contention that causes. Testcase: igt/gem_busy Signed-off-by:
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Chris Wilson authored
With a bit of care (and leniency) we can iterate over the object and wait for previous rendering to complete with judicial use of atomic reference counting. The ABI requires us to ensure that an active object is eventually flushed (like the busy-ioctl) which is guaranteed by our management of requests (i.e. everything that is submitted to hardware is flushed in the same request). All we have to do is ensure that we can detect when the requests are complete for reporting when the object is idle (without triggering ETIME), locklessly - this is handled by i915_gem_active_wait_unlocked(). The impact of this is actually quite small - the return to userspace following the wait was already lockless and so we don't see much gain in latency improvement upon completing the wait. What we do achieve here is completing an already finished wait without hitting the struct_mutex, our hold is quite short and so we are typically just a victim of contention rather than a cause - but it is still one less contention point! v2: Break up a long line. Signed-off-by:
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Chris Wilson authored
If we try and read or write to an active request, we first must wait upon the GPU completing that request. Let's do that without holding the mutex (and so allow someone else to access the GPU whilst we wait). Upon completion, we will acquire the mutex and only then start the operation (i.e. we do not rely on state from before the initial wait). v2: Repaint the goto labels v3: Move the tracepoints back to the start of the ioctls Signed-off-by:
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Chris Wilson authored
After removing the user of this wart, we can remove the wart entirely. Signed-off-by:
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Chris Wilson authored
If we make the observation that mmap-offsets are only released when we free an object, we can then deduce that the shrinker only creates free space in the mmap arena indirectly by flushing the request list and freeing expired objects. If we combine this with the lockless vma-manager and lockless idling, we can avoid taking our big struct_mutex until we need to actually free the requests. One side-effect is that we defer the madvise checking until we need the pages (i.e. the fault handler). This brings us into line with the other delayed checks (and madvise in general). v2: s/ret/err/ and use if (!err) rather than if (ret == 0) Signed-off-by:
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Chris Wilson authored
We can now wait for the GPU (all engines) to become idle without requiring the struct_mutex. Inside the shrinker, we need to currently take the struct_mutex in order to purge objects and to purge the objects we need the GPU to be idle - causing a stall whilst we hold the struct_mutex. We can hide most of that stall by performing the wait before taking the struct_mutex and only doing essential waits for new rendering on objects to be freed. Signed-off-by:
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Chris Wilson authored
Now that we pass along the expected interruptible nature for the wait-for-idle, we do not need to modify the global i915->mm.interruptible for this single call. (Only the immediate call to i915_gem_wait_for_idle() takes the interruptible status as the other action, dma_map_sg(), is independent of i915.ko) Signed-off-by:
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Chris Wilson authored
The principal motivation for this was to try and eliminate the struct_mutex from i915_gem_suspend - but we still need to hold the mutex current for the i915_gem_context_lost(). (The issue there is that there may be an indirect lockdep cycle between cpu_hotplug (i.e. suspend) and struct_mutex via the stop_machine().) For the moment, enabling last request tracking for the engine, allows us to do busyness checking and waiting without requiring the struct_mutex - which is useful in its own right. As a side-effect of having a robust means for tracking engine busyness, we can replace our other busyness heuristic, that of comparing against the last submitted seqno. For paranoid reasons, we have a semi-ordered check of that seqno inside the hangchecker, which we can now improve to an ordered check of the engine's busyness (removing a locked xchg in the process). v2: Pass along "bool interruptible" as being unlocked we cannot rely on i915->mm.interruptible being stable or even under our control. v3: Replace check Ironlake i915_gpu_busy() with the common precalculated value Signed-off-by:
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Chris Wilson authored
Before suspending (or unloading), we would first wait upon all rendering to be completed and then disable the rings. This later step is a remanent from DRI1 days when we did not use request tracking for all operations upon the ring. Now that we are sure we are waiting upon the very last operation by the engine, we can forgo clobbering the ring registers, though we do keep the assert that the engine is indeed idle before sleeping. Signed-off-by:
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Chris Wilson authored
Inside the kthread context, we can't be interrupted by signals so touching the mm.interruptible flag is pointless and wait-request now consumes EIO itself. Signed-off-by:
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Chris Wilson authored
We can completely avoid taking the struct_mutex around the non-blocking waits by switching over to the RCU request management (trading the mutex for a RCU read lock and some complex atomic operations). The improvement is that we gain further contention reduction, and overall the code become simpler due to the reduced mutex dancing. Signed-off-by:
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Chris Wilson authored
We can completely avoid taking the struct_mutex around the non-blocking waits by switching over to the RCU request management (trading the mutex for a RCU read lock and some complex atomic operations). The improvement is that we gain further contention reduction, and overall the code become simpler due to the reduced mutex dancing. v2: Move i915_gem_fault tracepoint back to the start of the function, before the unlocked wait. Signed-off-by:
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Chris Wilson authored
It is useful to be able to wait on pending rendering without grabbing the struct_mutex. We can do this by using the i915_gem_active_get_rcu() primitive to acquire a reference to the pending request without requiring struct_mutex, just the RCU read lock, and then call i915_wait_request(). v2: Rebase onto new i915_gem_active_get_unlocked() semantics that take the RCU read lock on behalf of the caller. Signed-off-by:
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Daniel Vetter authored
Backmerge the 4.8 pull request state from Dave - conflicts were getting out of hand, and Chris has some patches which outright don't apply without everything merged together again. Signed-off-by:Daniel Vetter <daniel.vetter@intel.com>
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Ville Syrjälä authored
The spec was recently fixed to have the correct iboost setting for the SKL Y/U DP DDI buffer translation table entry 2. Update our tables to match. Cc: David Weinehall <david.weinehall@linux.intel.com> Signed-off-by:
Ville Syrjälä <ville.syrjala@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1470140517-13011-1-git-send-email-ville.syrjala@linux.intel.com Cc: stable@vger.kernel.org Reviewed-by:
David Weinehall <david.weinehall@linux.intel.com>
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- 04 Aug, 2016 19 commits
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Matt Roper authored
The bspec was updated a couple weeks ago to add an extra block per line to plane watermark calculations for linear pixel formats. Bspec update 115327 description: "Gen9+ - Updated the plane blocks per line calculation for linear cases. Adds +1 for all linear cases to handle the non-block aligned stride cases." Cc: Lyude <cpaul@redhat.com> Cc: drm-intel-fixes@lists.freedesktop.org Signed-off-by:
Matt Roper <matthew.d.roper@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1470344880-27394-1-git-send-email-matthew.d.roper@intel.comReviewed-by:
Lyude <cpaul@redhat.com>
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Chris Wilson authored
If the GEM objects being rendered with in this request have been exported via dma-buf to a third party, hook ourselves into the dma-buf reservation object so that the third party can serialise with our rendering via the dma-buf fences. Testcase: igt/prime_busy Signed-off-by:
Daniel Vetter <daniel.vetter@ffwll.ch> Link: http://patchwork.freedesktop.org/patch/msgid/1470324762-2545-26-git-send-email-chris@chris-wilson.co.uk
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Chris Wilson authored
If we enable RCU for the requests (providing a grace period where we can inspect a "dead" request before it is freed), we can allow callers to carefully perform lockless lookup of an active request. However, by enabling deferred freeing of requests, we can potentially hog a lot of memory when dealing with tens of thousands of requests per second - with a quick insertion of a synchronize_rcu() inside our shrinker callback, that issue disappears. v2: Currently, it is our responsibility to handle reclaim i.e. to avoid hogging memory with the delayed slab frees. At the moment, we wait for a grace period in the shrinker, and block for all RCU callbacks on oom. Suggested alternatives focus on flushing our RCU callback when we have a certain number of outstanding request frees, and blocking on that flush after a second high watermark. (So rather than wait for the system to run out of memory, we stop issuing requests - both are nondeterministic.) Paul E. McKenney wrote: Another approach is synchronize_rcu() after some largish number of requests. The advantage of this approach is that it throttles the production of callbacks at the source. The corresponding disadvantage is that it slows things up. Another approach is to use call_rcu(), but if the previous call_rcu() is still in flight, block waiting for it. Yet another approach is the get_state_synchronize_rcu() / cond_synchronize_rcu() pair. The idea is to do something like this: cond_synchronize_rcu(cookie); cookie = get_state_synchronize_rcu(); You would of course do an initial get_state_synchronize_rcu() to get things going. This would not block unless there was less than one grace period's worth of time between invocations. But this assumes a busy system, where there is almost always a grace period in flight. But you can make that happen as follows: cond_synchronize_rcu(cookie); cookie = get_state_synchronize_rcu(); call_rcu(&my_rcu_head, noop_function); Note that you need additional code to make sure that the old callback has completed before doing a new one. Setting and clearing a flag with appropriate memory ordering control suffices (e.g,. smp_load_acquire() and smp_store_release()). v3: More comments on compiler and processor order of operations within the RCU lookup and discover we can use rcu_access_pointer() here instead. v4: Wrap i915_gem_active_get_rcu() to take the rcu_read_lock itself. Signed-off-by: -
Chris Wilson authored
Just move it earlier so that we can use the companion nonblocking version in a couple of more callsites without having to add a forward declaration. Signed-off-by:
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Chris Wilson authored
We are motivated to avoid using a bitfield for obj->active for a couple of reasons. Firstly, we wish to document our lockless read of obj->active using READ_ONCE inside i915_gem_busy_ioctl() and that requires an integral type (i.e. not a bitfield). Secondly, gcc produces abysmal code when presented with a bitfield and that shows up high on the profiles of request tracking (mainly due to excess memory traffic as it converts the bitfield to a register and back and generates frequent AGI in the process). v2: BIT, break up a long line in compute the other engines, new paint for i915_gem_object_is_active (now i915_gem_object_get_active). Signed-off-by:
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Chris Wilson authored
Rather than a mismash of struct drm_device *dev and struct drm_i915_private *dev_priv being used freely within a function, be consistent and only pass along dev_priv. Signed-off-by:
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Chris Wilson authored
The individual bits inside obj->frontbuffer_bits are protected by each plane->mutex, but the whole bitfield may be accessed by multiple KMS operations simultaneously and so the RMW need to be under atomics. However, for updating the single field we do not need to mandate that it be under the struct_mutex, one more step towards its removal as the de facto BKL. Signed-off-by:
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Chris Wilson authored
We only need a very lightweight mechanism here as the locking is only used for co-ordinating a bitfield. v2: Move the cheap unlikely tests into the caller v3: Move the kerneldoc into the header (now separated out into intel_fronbuffer.h for better kerneldoc and readability) Signed-off-by:
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Chris Wilson authored
In view of adding inline functions into the intel_frontbuffer section, we first split the header into its own file so that we can integrate it more easily with kerneldoc. Signed-off-by:
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Chris Wilson authored
Since i915_gem_obj_ggtt_pin() is an idiom breaking curry function for i915_gem_object_ggtt_pin(), spare us the confusion and remove it. Removing it now simplifies later patches to change the i915_vma_pin() (and friends) interface. v2: Add a redundant GEM_BUG_ON(!view) to i915_gem_obj_lookup_or_create_ggtt_vma() Signed-off-by:
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Chris Wilson authored
Not only is i915_vma_pin() called for every single object on every single execbuf, it is usually a simple increment as the VMA is already bound for execution by the GPU. Rearrange the tests for unbound and pin_count overflow so that we can do the increment and test very cheaply and compact enough to inline the operation into execbuf. The trick used is to note that we can check for an overflow bit (keeping space available for it inside the flags) at the same time as checking the binding bits. Signed-off-by:
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Chris Wilson authored
In preparation to perform some magic to speed up i915_vma_pin(), which is among the hottest of hot paths in execbuf, refactor all the bitfields accessed by i915_vma_pin() into a single unified set of flags. Signed-off-by:
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Chris Wilson authored
During execbuffer we look up the i915_vma in order to reserve them in the VM. However, we then do a double lookup of the vma in order to then pin them, all because we lack the necessary interfaces to operate on i915_vma - so introduce i915_vma_pin()! v2: Tidy parameter lists to remove one level of redirection in the hot path. Signed-off-by:
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Chris Wilson authored
In the next few patches, the VMA pinning API is overhauled and to reduce the churn we pull out the update to the accessors into a prep patch. Signed-off-by:
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Chris Wilson authored
Tracking the size of the VMA as allocated allows us to dramatically reduce the complexity of later functions (like inserting the VMA in to the drm_mm range manager). Signed-off-by:
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Chris Wilson authored
For consistency, internal functions should take drm_i915_private rather than drm_device. Now that we are subclassing drm_device, there are no more size wins, but being consistent is its own blessing. Signed-off-by:
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Chris Wilson authored
In order to be consistent with other address space functions, we want to pass around 64-bit sizes, even though all known global GTT are limited to 4GiB. Similarly, we are trying to be consistent in using the _ggtt_ nomenclature when referring to the special global GTT. v2: Update docs to consistently state "global GTT". Signed-off-by:
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Chris Wilson authored
As we always allocate in chunks of 4096 (that being both the PAGE_SIZE and our own GTT_PAGE_SIZE), we know that all results from the drm_mm are aligned to at least 4096. The drm_mm allocator itself is optimised for alignment == 0, and so by converting alignments of 4096 to 0 we can satisfy our own requirements and still hit the faster path. Signed-off-by:
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Chris Wilson authored
Split the insertion into the address space's range manager and binding of that object into the GTT to simplify the code flow when pinning a VMA. Signed-off-by:
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