On Thu, Jun 17, 2021 at 06:46:48PM +0200, Daniel Vetter wrote: > Sorry I'm behind on mails ... > Aren't we all. > On Fri, Jun 11, 2021 at 12:50:29PM -0700, Matthew Brost wrote: > > On Fri, Jun 04, 2021 at 07:59:05PM +0200, Daniel Vetter wrote: > > > On Wed, May 26, 2021 at 04:33:57PM -0700, Matthew Brost wrote: > > > > Add entry for i915 new parallel submission uAPI plan. > > > > > > > > v2: > > > > (Daniel Vetter): > > > > - Expand logical order explaination > > > > - Add dummy header > > > > - Only allow N BBs in execbuf IOCTL > > > > - Configure parallel submission per slot not per gem context > > > > v3: > > > > (Marcin Ślusarz): > > > > - Lot's of typos / bad english fixed > > > > (Tvrtko Ursulin): > > > > - Consistent pseudo code, clean up wording in descriptions > > > > > > > > Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> > > > > Cc: Tony Ye <tony.ye@xxxxxxxxx> > > > > CC: Carl Zhang <carl.zhang@xxxxxxxxx> > > > > Cc: Daniel Vetter <daniel.vetter@xxxxxxxxx> > > > > Cc: Jason Ekstrand <jason@xxxxxxxxxxxxxx> > > > > Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx> > > > > --- > > > > Documentation/gpu/rfc/i915_parallel_execbuf.h | 145 ++++++++++++++++++ > > > > Documentation/gpu/rfc/i915_scheduler.rst | 55 ++++++- > > > > 2 files changed, 198 insertions(+), 2 deletions(-) > > > > create mode 100644 Documentation/gpu/rfc/i915_parallel_execbuf.h > > > > > > > > diff --git a/Documentation/gpu/rfc/i915_parallel_execbuf.h b/Documentation/gpu/rfc/i915_parallel_execbuf.h > > > > new file mode 100644 > > > > index 000000000000..20de206e3ab4 > > > > --- /dev/null > > > > +++ b/Documentation/gpu/rfc/i915_parallel_execbuf.h > > > > @@ -0,0 +1,145 @@ > > > > +#define I915_CONTEXT_ENGINES_EXT_PARALLEL_SUBMIT 2 /* see i915_context_engines_parallel_submit */ > > > > + > > > > +/* > > > > + * i915_context_engines_parallel_submit: > > > > > > So the idea is to make these kerneldoc and pull them into the rfc section. > > > Then when we merge, move them to the real uapi section, like what Matt has > > > done for lmem. > > > > > > > Yep, will fix in next rev. > > > > > > + * > > > > + * Setup a slot in the context engine map to allow multiple BBs to be submitted > > > > + * in a single execbuf IOCTL. Those BBs will then be scheduled to run on the GPU > > > > + * in parallel. Multiple hardware contexts are created internally in the i915 > > > > + * run these BBs. Once a slot is configured for N BBs only N BBs can be > > > > + * submitted in each execbuf IOCTL and this is implicit behavior e.g. The user > > > > + * doesn't tell the execbuf IOCTL there are N BBs, the execbuf IOCTL know how > > > > + * many BBs there are based on the slots configuration. The N BBs are the last N > > > > + * buffer objects for first N if I915_EXEC_BATCH_FIRST is set. > > > > > > s/for/or/ > > > > > > > + * > > > > + * There are two currently defined ways to control the placement of the > > > > + * hardware contexts on physical engines: default behavior (no flags) and > > > > + * I915_PARALLEL_IMPLICIT_BONDS (a flag). More flags may be added the in the > > > > + * future as new hardware / use cases arise. Details of how to use this > > > > + * interface above the flags field in this structure. > > > > + * > > > > + * Returns -EINVAL if hardware context placement configuration is invalid or if > > > > + * the placement configuration isn't supported on the platform / submission > > > > + * interface. > > > > + * Returns -ENODEV if extension isn't supported on the platform / submission > > > > + * inteface. > > > > + */ > > > > +struct i915_context_engines_parallel_submit { > > > > + struct i915_user_extension base; > > > > + > > > > + __u16 engine_index; /* slot for parallel engine */ > > > > > > Kernel doc here for the inline comments too. > > > > > > > Yep. > > > > > > + __u16 width; /* number of contexts per parallel engine */ > > > > + __u16 num_siblings; /* number of siblings per context */ > > > > + __u16 mbz16; > > > > +/* > > > > + * Default placement behavior (currently unsupported): > > > > + * > > > > + * Allow BBs to be placed on any available engine instance. In this case each > > > > + * context's engine mask indicates where that context can be placed. It is > > > > + * implied in this mode that all contexts have mutual exclusive placement. > > > > + * e.g. If one context is running CSX[0] no other contexts can run on CSX[0]). > > > > + * > > > > + * Example 1 pseudo code: > > > > + * CSX,Y[N] = generic engine class X or Y, logical instance N > > > > + * INVALID = I915_ENGINE_CLASS_INVALID, I915_ENGINE_CLASS_INVALID_NONE > > > > + * set_engines(INVALID) > > > > + * set_parallel(engine_index=0, width=2, num_siblings=2, > > > > + * engines=CSX[0],CSX[1],CSY[0],CSY[1]) > > > > + * > > > > + * Results in the following valid placements: > > > > + * CSX[0], CSY[0] > > > > + * CSX[0], CSY[1] > > > > + * CSX[1], CSY[0] > > > > + * CSX[1], CSY[1] > > > > + * > > > > + * This can also be thought of as 2 virtual engines described by 2-D array in > > > > + * the engines the field: > > > > + * VE[0] = CSX[0], CSX[1] > > > > + * VE[1] = CSY[0], CSY[1] > > > > + * > > > > + * Example 2 pseudo code: > > > > + * CSX[Y] = generic engine of same class X, logical instance N > > > > + * INVALID = I915_ENGINE_CLASS_INVALID, I915_ENGINE_CLASS_INVALID_NONE > > > > + * set_engines(INVALID) > > > > + * set_parallel(engine_index=0, width=2, num_siblings=3, > > > > + * engines=CSX[0],CSX[1],CSX[2],CSX[0],CSX[1],CSX[2]) > > > > + * > > > > + * Results in the following valid placements: > > > > + * CSX[0], CSX[1] > > > > + * CSX[0], CSX[2] > > > > + * CSX[1], CSX[0] > > > > + * CSX[1], CSX[2] > > > > + * CSX[2], CSX[0] > > > > + * CSX[2], CSX[1] > > > > + * > > > > + * This can also be thought of as 2 virtual engines described by 2-D array in > > > > + * the engines the field: > > > > + * VE[0] = CSX[0], CSX[1], CSX[2] > > > > + * VE[1] = CSX[0], CSX[1], CSX[2] > > > > + > > > > + * This enables a use case where all engines are created equally, we don't care > > > > + * where they are scheduled, we just want a certain number of resources, for > > > > + * those resources to be scheduled in parallel, and possibly across multiple > > > > + * engine classes. > > > > + */ > > > > + > > > > +/* > > > > > > Would be good to also move this into the kerneldoc (maybe add labelled > > > list for flags or so) so it shows up in the render output. > > > > > > > Sure. I need figure out view the kernel doc locally before my next and make sure > > everything looks right. > > $ make htmldocs > > Output is in Documentation/output/gpu/index.html (to get there more > directly). > I've figured this out, next rev of docs looks good to me. > > > > > > + * I915_PARALLEL_IMPLICIT_BONDS - Create implicit bonds between each context. > > > > + * Each context must have the same number of sibling and bonds are implicitly > > > > + * created between each set of siblings. > > > > + * > > > > + * Example 1 pseudo code: > > > > + * CSX[N] = generic engine of same class X, logical instance N > > > > + * INVALID = I915_ENGINE_CLASS_INVALID, I915_ENGINE_CLASS_INVALID_NONE > > > > + * set_engines(INVALID) > > > > + * set_parallel(engine_index=0, width=2, num_siblings=1, > > > > + * engines=CSX[0],CSX[1], flags=I915_PARALLEL_IMPLICIT_BONDS) > > > > + * > > > > + * Results in the following valid placements: > > > > + * CSX[0], CSX[1] > > > > + * > > > > + * Example 2 pseudo code: > > > > + * CSX[N] = generic engine of same class X, logical instance N > > > > + * INVALID = I915_ENGINE_CLASS_INVALID, I915_ENGINE_CLASS_INVALID_NONE > > > > + * set_engines(INVALID) > > > > + * set_parallel(engine_index=0, width=2, num_siblings=2, > > > > + * engines=CSX[0],CSX[2],CSX[1],CSX[3], > > > > + * flags=I915_PARALLEL_IMPLICIT_BONDS) > > > > + * > > > > + * Results in the following valid placements: > > > > + * CSX[0], CSX[1] > > > > + * CSX[2], CSX[3] > > > > + * > > > > + * This can also be thought of as 2 virtual engines described by 2-D array in > > > > + * the engines the field with bonds placed between each index of the virtual > > > > + * engines. e.g. CSX[0] is bonded to CSX[1], CSX[2] is bonded to CSX[3]. > > > > + * VE[0] = CSX[0], CSX[2] > > > > + * VE[1] = CSX[1], CSX[3] > > > > + * > > > > + * This enables a use case where all engines are not equal and certain placement > > > > + * rules are required (i.e. split-frame requires all contexts to be placed in a > > > > + * logically contiguous order on the VCS engines on gen11+ platforms). This use > > > > + * case (logically contiguous placement, within a single engine class) is > > > > + * supported when using GuC submission. Execlist mode could support all possible > > > > + * bonding configurations but currently doesn't support this extension. > > > > + */ > > > > +#define I915_PARALLEL_IMPLICIT_BONDS (1 << 0) > > > > +/* > > > > + * Do not allow BBs to be preempted mid BB rather insert coordinated preemption > > > > + * points on all hardware contexts between each set of BBs. An example use case > > > > + * of this feature is split-frame on gen11+ hardware. > > > > + */ > > > > +#define I915_PARALLEL_NO_PREEMPT_MID_BATCH (1 << 1) > > > > > > So I get the history now behind this, but I think specifying flags for the > > > only behaviour you can get and the only behaviour that userspace asks for > > > is silly. > > > > > > I think we should just move the actual behaviour spec into the kerneldoc, > > > as in "this is the bonding you get" and "due to hw/fw limitations these > > > workloads will be non-preemptable" and call it a day. Trying to guess > > > future needs and specifying them, without knowing those future needs > > > precisely, much less having an implementation, just never works out > > > really. > > > > > > > So no flags? Or just the default behavior is I915_PARALLEL_IMPLICIT_BONDS | > > I915_PARALLEL_NO_PREEMPT_MID_BATCH for now, the flags are unused, but could be > > used in the future if needed? > > The implicit_bonds I think should be just the default, we can add flags > for the other stuff when it exist. > Yep, next rev this is the default. > The NO_PREEMPT I think makes some sense to keep to make this part > explicit. Either way on that is fine with me. > Ok, my next rev made this the default behavior. Either way, not a big deal or enough to respin this DoC as it is only the DoC. We can make a choice on the NO_PREEMPT when the code lands. > > > I discussed this a bit with Jason, and he's suggested this makes sense as > > > a engine flag, but definitely not on the parallel extension. But since we > > > > Not sure what you mean by an engine flags. This is a per context concept. > > Oh, I guess this is more fallout from the conversion from having the > entire gem context as the parallel submit vehicle to a virtual engine. > > If we do have them as flags, they need to be on that virtual engine, not > on the overall gem context container thing. At that point they don't > exactly match up the existing preempt flag we have (on the context), so > maybe we should just make this implied (but ofc documented) behaviour. > Got it. Matt > Cheers, Daniel > > > > > > don't have a need for picking a non-default value just extra work. > > > > > > > +#define __I915_PARALLEL_UNKNOWN_FLAGS (-(I915_PARALLEL_NO_PREEMPT_MID_BATCH << 1)) > > > > + __u64 flags; /* all undefined flags must be zero */ > > > > + __u64 mbz64[3]; /* reserved for future use; must be zero */ > > > > + > > > > + /* > > > > + * 2-D array of engines > > > > + * > > > > + * width (i) * num_siblings (j) in length > > > > + * index = j + i * num_siblings > > > > + */ > > > > + struct i915_engine_class_instance engines[0]; > > > > +} __attribute__ ((packed)); > > > > + > > > > diff --git a/Documentation/gpu/rfc/i915_scheduler.rst b/Documentation/gpu/rfc/i915_scheduler.rst > > > > index 7faa46cde088..0254c04d34be 100644 > > > > --- a/Documentation/gpu/rfc/i915_scheduler.rst > > > > +++ b/Documentation/gpu/rfc/i915_scheduler.rst > > > > @@ -23,7 +23,7 @@ i915 with the DRM scheduler is: > > > > severe design issues in general, which is why we want to retire it no > > > > matter what > > > > * New uAPI adds I915_CONTEXT_ENGINES_EXT_PARALLEL context setup step > > > > - which configures a slot with N contexts > > > > + which configures a slot with N contexts > > > > * After I915_CONTEXT_ENGINES_EXT_PARALLEL a user can submit N batches to > > > > a slot in a single execbuf IOCTL and the batches run on the GPU in > > > > paralllel > > > > @@ -82,4 +82,55 @@ https://spec.oneapi.com/level-zero/latest/core/api.html#ze-command-queue-priorit > > > > > > > > New parallel submission uAPI > > > > ============================ > > > > -Details to come in a following patch. > > > > +The existing bonding uAPI is completely broken with GuC submission because > > > > +whether a submission is a single context submit or parallel submit isn't known > > > > +until execbuf time activated via the I915_SUBMIT_FENCE. To submit multiple > > > > +contexts in parallel with the GuC the context must be explicitly registered with > > > > +N contexts and all N contexts must be submitted in a single command to the GuC. > > > > +The GuC interfaces do not support dynamically changing between N contexts as the > > > > +bonding uAPI does. Hence the need for a new parallel submission interface. Also > > > > +the legacy bonding uAPI is quite confusing and not intuitive at all. > > > > > > We should add here that "Furthermore I915_SUBMIT_FENCE is by design a > > > future fence, so not really something we should continue to support." > > > > > > > + > > > > +The new parallel submission uAPI consists of 3 parts: > > > > + > > > > +* Export engines logical mapping > > > > +* A 'set_parallel' extension to configure contexts for parallel > > > > + submission > > > > +* Extend execbuf2 IOCTL to support submitting N BBs in a single IOCTL > > > > + > > > > +Export engines logical mapping > > > > +------------------------------ > > > > +Certain use cases require BBs to be placed on engine instances in logical order > > > > +(e.g. split-frame on gen11+). The logical mapping of engine instances can change > > > > +based on fusing. Rather than making UMDs be aware of fusing, simply expose the > > > > +logical mapping with the existing query engine info IOCTL. Also the GuC > > > > +submission interface currently only supports submitting multiple contexts to > > > > +engines in logical order which is a new requirement compared to execlists. > > > > +Lastly, all current platforms have at most 2 engine instances and the logical > > > > +order is the same as uAPI order. This will change on platforms with more than 2 > > > > +engine instances. > > > > + > > > > +A single bit will be added to drm_i915_engine_info.flags indicating that the > > > > +logical instance has been returned and a new field, > > > > +drm_i915_engine_info.logical_instance, returns the logical instance. > > > > + > > > > +A 'set_parallel' extension to configure contexts for parallel submission > > > > +------------------------------------------------------------------------ > > > > +The 'set_parallel' extension configures a slot for parallel submission of N BBs. > > > > +It is setup step that should be called before using any of the contexts. See > > > > > > s/should/must/ > > > > > > We've made it a CTX_CREATE_EXT extension, so really you don't have a > > > choice anymore :-) > > > > Right, this can only be called at context creation. > > > > > > > > > +I915_CONTEXT_ENGINES_EXT_LOAD_BALANCE or I915_CONTEXT_ENGINES_EXT_BOND for > > > > +similar existing examples. Once a slot is configured for parallel submission the > > > > +execbuf2 IOCTL can be called submitting N BBs in a single IOCTL. Initially only > > > > +support GuC submission. Execlist support can be added later if needed. > > > > + > > > > +Add I915_CONTEXT_ENGINES_EXT_PARALLEL_SUBMIT and > > > > +i915_context_engines_parallel_submit to the uAPI to implement this extension. > > > > + > > > > +Extend execbuf2 IOCTL to support submitting N BBs in a single IOCTL > > > > +------------------------------------------------------------------- > > > > +Contexts that have been configured with the 'set_parallel' extension are allowed > > > > +to submit N BBs in a single execbuf2 IOCTL. The BBs are either the last N > > > > +objects in the drm_i915_gem_exec_object2 list or the first N if > > > > +I915_EXEC_BATCH_FIRST is set. The number of BBs is implict based on the slot > > > > +submitted and how it has been configured by 'set_parallel' or other extensions. > > > > +No uAPI changes are required to execbuf2 IOCTL. > > > > > > Addd here the kerneldoc include for your header. > > > > > > > Sure. > > > > Matt > > > > > Aside from the comments by and large this looks good. The main interface > > > at least is clear and warts-free. > > > > > > Acked-by: Daniel Vetter <daniel.vetter@xxxxxxxx> > > > > > > > -- > > > > 2.28.0 > > > > > > > > _______________________________________________ > > > > Intel-gfx mailing list > > > > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > > > > https://lists.freedesktop.org/mailman/listinfo/intel-gfx > > > > > > -- > > > Daniel Vetter > > > Software Engineer, Intel Corporation > > > http://blog.ffwll.ch > > -- > Daniel Vetter > Software Engineer, Intel Corporation > http://blog.ffwll.ch