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Module Rig_nv_abi.Gpfifo

Ring entries.

A channel's ring, its GPFIFO, holds 64-bit entries, each naming a segment of a pushbuffer. The channel fetches the entries in order and runs each segment's words (Method).

Compiled code hands one of the GPU's queues work as words alone: ring entries, each as two 32-bit words, low first. Each entry names a segment of the GPU's memory that compiled code wrote and must keep until the work completes. The driver places the entries in the queue's ring after its wait for earlier work and before its signal of the work's value, so compiled code leaves waits and releases to the driver.

#val max_words : int

max_words is the most words a segment holds, 2{^21} - 1.

#val entry : Template.operand -> offset:int -> words:int -> Template.t

entry addr ~offset ~words is the entry of the segment of words words at addr + offset, which is 4-byte aligned and below 2{^40}. The entry is Template.u64 n addr, where n depends on offset and words alone: a writer encodes the entry once with the address 0, which gives n, and adds each segment's address. Bit 63 of an entry, which would make the channel wait for its earlier work, is clear.

Raises Invalid_argument if words is outside [0;max_words] or offset is outside [0;2{^40}-1].