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tensor: Fix commit/metadata logic for HGMMA

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Block HGMMA commit until previous ones are all done; always commit
HGMMA_WAIT after it passes the scoreboard.
This commit is contained in:
Hansung Kim
2024-10-22 20:01:37 -07:00
parent 3abaaff16f
commit 47dff74d3a
1 changed files with 42 additions and 28 deletions
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70
hw/rtl/core/VX_tensor_hopper_core.sv
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@@ -90,9 +90,10 @@ module VX_tensor_hopper_core_block import VX_gpu_pkg::*; #(
logic writeback_ready;
wire metadata_valid = ~metadata_queue_emptys[0/*FIXME*/];
wire not_wait = metadata_valid && (execute_if_data_op_type[0] != `INST_TENSOR_HGMMA_WAIT);
wire hmma_wait = metadata_valid &&
(execute_if_data_op_type[0] == `INST_TENSOR_HGMMA_WAIT);
// skip HGMMA_WAIT for kickoff
wire initiate_valid = metadata_valid && not_wait;
wire initiate_valid = metadata_valid && !hmma_wait;
// we're recycling execute_if.op_type as operands_if.op_type which might
// have a different width; let's be safe
@@ -156,40 +157,40 @@ module VX_tensor_hopper_core_block import VX_gpu_pkg::*; #(
// );
wire [`NUM_THREADS-1:0][`XLEN-1:0] wb_data = '0;
logic commit_select_tensor;
always @(*) begin
metadata_deq = 1'b0;
// if there's something in the meta queue, give it priority for commit,
// since every HGMMA instructions are asynchronous and should not
// block
// 1'b0: commit from metadata queue
// 1'b1: commit from tensor core writeback output
commit_select_tensor = 1'b0;
writeback_ready = commit_if.ready;
// if there's something in the meta queue, give it priority for commit
// to keep asynchrony of HGMMA instructions. note HGMMA's should be
// stalled if the tensor core is already busy.
if (metadata_valid) begin
// block tensor core writeback
writeback_ready = 1'b0;
if (hmma_wait) begin
// block tensor core writeback
writeback_ready = 1'b0;
commit_if.valid = metadata_valid;
commit_if.data.uuid = execute_if_data_uuid[0];
commit_if.data.wid = execute_if_data_wid[0];
commit_if.data.tmask = execute_if_data_tmask[0];
commit_if.data.PC = execute_if_data_PC[0];
commit_if.data.wb = execute_if_data_wb[0];
commit_if.data.rd = execute_if_data_rd[0];
commit_if.data.data = wb_data; // FIXME ?
commit_if.data.tensor = 1'b0;
commit_if.data.pid = 1'b0;
commit_if.data.sop = 1'b1;
commit_if.data.eop = 1'b1;
// block meta queue until tensor core is ready. This will
// effectively stall further issue of async HGMMA when tensor core
// is busy with too many outstanding requests (depth of meta queue).
// be careful to not miss the commit backpressure.
metadata_deq = metadata_valid && commit_if.ready && initiate_ready;
// commit HGMMA_WAIT regardless of tensor core busy
commit_select_tensor = 1'b0;
metadata_deq = metadata_valid && commit_if.ready;
end else begin
// hold commit and meta dequeue until tensor core is ready.
// This will stall newer HGMMAs when tensor core is already
// busy with an older one.
commit_select_tensor = !initiate_ready;
metadata_deq = metadata_valid && commit_if.ready && initiate_ready;
end
end else begin
// allow tensor core writeback, provided there's no commit
// backpressure
writeback_ready = commit_if.ready;
commit_select_tensor = 1'b1;
end
if (commit_select_tensor) begin
commit_if.valid = writeback_valid;
commit_if.data.uuid = '0;
commit_if.data.wid = '0; // FIXME
@@ -204,6 +205,19 @@ module VX_tensor_hopper_core_block import VX_gpu_pkg::*; #(
// only the last ghost commit has eop set, which will trigger
// scoreboard to clear out the busy bit.
commit_if.data.eop = writeback_last;
end else begin
commit_if.valid = metadata_valid;
commit_if.data.uuid = execute_if_data_uuid[0];
commit_if.data.wid = execute_if_data_wid[0];
commit_if.data.tmask = execute_if_data_tmask[0];
commit_if.data.PC = execute_if_data_PC[0];
commit_if.data.wb = execute_if_data_wb[0];
commit_if.data.rd = execute_if_data_rd[0];
commit_if.data.data = wb_data; // FIXME ?
commit_if.data.tensor = 1'b0;
commit_if.data.pid = 1'b0;
commit_if.data.sop = 1'b1;
commit_if.data.eop = 1'b1;
end
end