From 2026fa7084b82a64836d946c4bb93d2996961096 Mon Sep 17 00:00:00 2001 From: Arthur Hanson Rasmusson Date: Sun, 4 Oct 2026 18:54:35 -0400 Subject: vgsp: once-only op execution per entry identity, per-op done bitmap The pump's operand-targeted-scan hold decodes a push, runs every op that translates, then leaves the entry pending for a retry. The retry re-decoded the whole push and re-ran the operations that had already completed. A CE copy reads a client staging buffer the client refills per chunk, so the retry overwrote a finished chunk with the following chunk's data (observed: the bridge's vadd input half replaced by the next 1 MB chunk, first half of the device buffer byte-identical to the source shifted by exactly 2 MB; the same 1 MB copy logged twice with different staging contents). The service now records, per GPFIFO slot, the entry identity plus a bitmap of the decoded operation indexes whose work has executed for that identity, and a complete flag for a pass that ended with no operand pending. svc_run_ops skips already-executed ops on a retry and marks the rest as they succeed; the pump stores the record immediately after decode, before any hold path can break, so the pending path can no longer lose it. A replay of a complete identity suppresses all ops; a partial identity retries only what is owed. Also carries the ops_once diagnostic counter in the service snapshot line and documents the operation-granularity rule in the architecture doc. --- docs/03-architecture/06-host-module-and-hybrid-model.md | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'docs') diff --git a/docs/03-architecture/06-host-module-and-hybrid-model.md b/docs/03-architecture/06-host-module-and-hybrid-model.md index dbf0c00..73349e8 100644 --- a/docs/03-architecture/06-host-module-and-hybrid-model.md +++ b/docs/03-architecture/06-host-module-and-hybrid-model.md @@ -256,6 +256,19 @@ pipeline: The same page-granular discipline already applies to the host-side bridge read/write helpers and to semaphore I/O. +Rule 1 holds at *operation* granularity as well as per entry. A push whose +decode finds one operand still under targeted translation is left pending and +decoded again on the next pass; the operations that already ran before the +hold must not run again. The service therefore records, per slot, the +identity of the entry plus a bitmap of the decoded operation indexes whose +work has executed for that identity. A retry skips those operations and only +re-attempts the ones that did not run; once a pass completes with no operand +left pending, a replay of the identity suppresses all operations. This +closes the hole where a held-and-retried entry re-ran a completed 1 MB +staging copy after the client refilled the staging buffer, overwriting a +finished chunk with the following chunk's data (observed once in fourteen +live cycles before the fix). + ## 5. The forwarding path (design) ``` -- cgit v1.2.3