From 09730aadb70ffda15b8e1c55fbb7322c9e0926a5 Mon Sep 17 00:00:00 2001 From: Arthur Hanson Rasmusson Date: Sun, 25 Oct 2026 09:02:49 -0400 Subject: wall-2 session-81: counter-autoreg gap analysed - svc_counter_autoreg needs an ipin pin or svc_counter_derive for the rank slot (0x20400fec0+(19-r)*0x10); both miss for the counter page 0x20400f000 (the client does not map it - pagemap empty, no VMA; it is a UVM kernel object; the pin stream's sem resolutions are 0 despite 44 want-list entries); bypass: the sema_counter param registers a slot manually (echo ,); GL ranks 0,1,2 -> slots 0x20400ffd0/0xfc0/0xfb0 --- tools/guest-diag/wall2/README-session77.md | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) (limited to 'tools') diff --git a/tools/guest-diag/wall2/README-session77.md b/tools/guest-diag/wall2/README-session77.md index 2eac8f4..82e162b 100644 --- a/tools/guest-diag/wall2/README-session77.md +++ b/tools/guest-diag/wall2/README-session77.md @@ -154,3 +154,32 @@ the A8 counter tables' source (what fills r14+0x5e8 / the "wanted" table - likely the GR channel's own progress counters) or the GR forward/ucode execution (`forwarded=0 gr_nocap=7` still). + +## ADDENDUM (r686, session 81) — the counter-autoreg gap analysed: the counter page 0x20400f000 is unresolvable; the manual `sema_counter` registration is the bypass + +* `svc_counter_autoreg` (per-pass for eng==0 channels, n_gr=20) needs a + translation for the rank slot VA `0x20400fec0 + (19-r)*0x10` + (r = gr_index = rank by ascending handle among the guest's GR + channels): either an ipin pin (`svc_ipin_lookup`, 9275 entries live + from the guest pin stream) or `svc_counter_derive` (the + vaspaces/discovered/targeted walk chain, `sema_counter_derive=1` + default). Both miss for the counter page -> no "counter auto" log, + `pub_calls=0` -> the A8 loop's per-entry counter tables never fill and + the NvOgl wait spins. +* The client does NOT map the counter pool: `/proc//pagemap` for + 0x20400f000/0x20400ffd0/0x20400ffc0/0x20400ffb0 is all-zero (not + present) and no VMA covers it - it is a UVM kernel-side object, so the + pin stream cannot resolve it through the client's page tables. The + stream's log shows `sem=0` (zero semaphore resolutions) even though + the want-list (`/tmp/guest_want_vas.txt`, host-written) contains 44 + `20400f` entries; the stream's "channel-anchored expansion" for the + UVM tracking sems (guest_pin_stream.py ~line 950-1010) is the + machinery that must find them (it is written for the CUDA second-client + stall - "the only live uvmt event is the spinning sem"). +* Bypass available now: the `sema_counter` parameter registers a channel + slot manually - `echo , > .../parameters/sema_counter`. + Once the counter page's PA is known (via the guest kcore/UVM walk), + this wires the publish path without a kernel rebuild. +* The rank slots for the GL client's channels (handles 0xbeec0100, + 0xbeec0104, 0xbeee0100 -> ranks 0,1,2): 0x20400ffd0 / 0x20400ffc0 / + 0x20400ffb0. -- cgit v1.2.3