hexagon: improved Op queuing, buffer and cache management (#21705)

* hexagon: introduce op request batching and rewrite buffer managment

The host now prepares batches of requests and dispatches them via a single dspqueue message.

Buffers are mapped explicitly by NPU while processing batches.

* hex-dma: disable l2 bypass since to work around new issue due to no flushes between Ops

* hex-utils: add explicit l2flush and l2clear helpers

* hex-opreq: use fine-grain per tensor l2 management

* hex-opreq: avoid redundant invalidates for tensors we already flushed

* hex-opreq: update debug messages

* htp-opreq: reuse ops_context

* hex-opreq: do not flush or invalidate cache lines beyond buffer boundry

* hex-opreq: fix errors in log message

* Revert "hex-opreq: do not flush or invalidate cache lines beyond buffer boundry"

This reverts commit 8b7f0a55a750a6430ce4eb1874c7feb3d720056d.

* hexagon: limit l2 flushes to 1MB which covers l2 cache

* hex-opreq: limit cache flush to 4MB

Looks like 4MB cont. vitual space should cover the 1MB cache.

* hexagon: drop cache flush size to 2MB

* hex-opreq: start reworking opreq packing

* hex-opreq: introduce new way of packing opbatch where tensors are stored separately

* hex-opreq: add a simple fastrpc call to force unmap all buffers

* hex-l2flush: somehow 2MB does not seem robust, also cleanup step size to use line-size

* hex-opreq: bump opreq batch size to 256

* hex-mm: place src1 spad at the top of vtcm for easy reuse

* hex-ops: introduce internal types and disable src1 reuse for now

Nothing new just formalizing the repack / qyn.quant types we've been using.

* htp-opreq: use tensor pointers instead of copies

* hex-opreq: introduce more robust way for tracking vtcm/spad reuse

This removes the SKIP_QUANTIZE flag that became fragile with the addition of HMX and other ops.

* hex-cumsum: fix error post opreq merge

* hex-opreq: move request batch handling into the session

Prepping everything for using dspqueue buffers and doing that inside the session is much cleaner.

* hex-mm: yet another fix for src1 reuse when we're mixing hmx/hvx

* hex-bufs: introduce pinned mmapings and use non-pinned ones for model buffers

* hex-buf: add support for allocating shared/pinned buffer for opreqs

* hex-opbatch: make opbatches configurable

* hex-naming: better name for ggml_hexagon_shared_buffer

* hex-naming: add session->c_name() helper

* hex-opbatch: start using shm but still copy for now

* hex-opbatch: use shared buffer for packing opbatch

* hex-opbatch: beter naming for opbatch related classes and code

* hex-opbatch: reuse batched tensors with same data/dims/strides

* hex-opbatch: update logging

* hex-opbatch: add support for vmem limit for op batching

* hex-opbatch: update htp side to properly support dynamic mmap/unmap

* hex-opbatch: add OB and OQ params for run-completion script and fix the asserts in batch processing

* hex-opbatch: fixed src1 handling in act ops

* hex-act: fix empty src1 handling in swiglu and friends

Simplify preamble macro while at it

* hex-mm: minor fix vtcm and dma handling in matmul

cleaning up some left-overs from merges

* hex-opbatch: allocate extra 1KB for dspqueue overhead

* hexagon: fix softmax for non-aligned tensors and cleanup vtcm alloc

* hex-mm: properly handle hmx_disabled flag

* hex-ops: update comments

* hex-ops: add debug output for get/set-rows

* hex-mmap: optimize un/mapping of buffers

* hex-opreq: global cache flush and invalidate beyond 128KB threshold

* hex-ops: add super simple opfilter regex for debugging

If an Op matches the regex hex backend will reject it.

* hex-opbatch: wireup newer ops missed in merge and update main switch to detect this in future

* hexagon: improved vtcm acquision to remove inter-op overhead

Fully compatible with QNN-HTP coex

* hex-mm: fixed hvx fallback path

* hex-mm: lower the vmem threshold a bit further to ~3GB

* hexagon: update debug & error logs

This also fixes an issue with newer llvm merging repack and non-repack
functions. We use those pointer to distinguish between buffer types.

* hexagon: move ops context into main context

Just a cleanup. We don't need separate contexts at this point.

* hex-opbatch: cleanup naming and headers for opbatch and related descriptors

* hex-fa: it's now better to enable FA during TG to reduce graph splits

* hexagon: remove GGML_HEXAGON_EXPERIMENTAL env var

It's no longer useful. Please use more flexible GGML_HEXAGON_OPFILTER to disable Ops
if needed for debugging or validation.

* hexagon: fixed editorconfig check

* Update ggml/src/ggml-hexagon/ggml-hexagon.cpp

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

---------

Co-authored-by: Trivikram Reddy <tamarnat@qti.qualcomm.com>
Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

docs/backend/snapdragon/README.md

@@ -236,10 +236,6 @@ build: 6a8cf8914 (6733)
   Controls whether the Hexagon backend allocates host buffers. By default, all buffers except for REPACK are host buffers.
   This option is required for testing Ops that require REPACK buffers (MUL_MAT and MUL_MAT_ID).
 
-- `GGML_HEXAGON_EXPERIMENTAL=1`
-  Controls whether the Hexagon backend enables experimental features.
-  This option is required for enabling/testing experimental Ops (FLASH_ATTN_EXT).
-
 - `GGML_HEXAGON_VERBOSE=1`
   Enables verbose logging of Ops from the backend. Example output:
 
@@ -259,11 +255,17 @@ build: 6a8cf8914 (6733)
   Allows enabling specific stages of the processing pipeline:
 
   - `0x1` Enable Op Queue (i.e., queuing Ops into NPU)
-  - `0x2` Enable Dynamic Quantizer (if needed for the Op)
-  - `0x4` Enable Op Compute (MUL_MAT, etc.)
+  - `0x2` Enable Op Compute (MUL_MAT, etc.)
 
   Examples:
 
       `GGML_HEXAGON_OPMASK=0x1 llama-completion ...` - Ops are enqueued but NPU-side processing is stubbed out
-      `GGML_HEXAGON_OPMASK=0x3 llama-completion ...` - NPU performs dynamic quantization and skips the rest
-      `GGML_HEXAGON_OPMASK=0x7 llama-completion ...` - Full queuing and processing of Ops (default)
+      `GGML_HEXAGON_OPMASK=0x3 llama-completion ...` - Full queuing and processing of Ops (default)
+
+- `GGML_HEXAGON_OPFILTER=regex`
+  Allows filtering (disabling) Ops that match the regex pattern:
+
+  Examples:
+
+      `GGML_HEXAGON_OPFILTER="FLASH_ATTN_EXT" llama-completion ...` - Disable Flash Attention on Hexagon (falls back to CPU or GPU)
+      `GGML_HEXAGON_OPFILTER="ADD\|SUB" llama-completion ...` - Disable ADD and SUB on Hexagon (fall back to CPU or GPU)