From 9813c9b9b6d9fa7e56fe0e77ccd4589fd9e90902 Mon Sep 17 00:00:00 2001 From: Arthur Hanson Rasmusson Date: Sun, 25 Oct 2026 05:57:04 -0400 Subject: wall-2 session 74: the client's 11s stalls are userspace completion-slot spins; the next wall is the polled RM control 0x2080a097 Root-caused the vk_frame client's exact 11.00s gaps: a pure sched_yield + clock_gettime userspace spin inside libnvidia-eglcore's EGL/GL init, waiting for completion slots (u16 at slot+0xe == 0xffff) in /dev/nvidiactl mappings. Guest-side filling of the slot flags lets the client proceed immediately, but vkCreateDevice still fails -4: with the slots filled the client settles into an NVOS54 poll of RM control 0x2080a097 (paramsSize=1168) which our emulation answers with the generic all-zero reply, so the poll never completes. Also captured: sema_push_raw dumps proving the GR channel-init push contains NO release (entry0 decodes 2 methods then zeros; entry2 SET_OBJECT 0xc597 then zeros), and the negative result that neither channelFillGpFifo nor nvWriteGpEntry runs for this channel's kick. New probes: gdbpoll6/gdbu16/gdbfill/gdbwatch/gdbparam/gdbgap3/gdbspin (slot check, flag fill, NVOS54 param dump, backtraces), slotfill{,2}.sh (guest slot watcher), stracevk/fastrun{,2}.sh (strace+perf recipes), find_ring_va.py and vmap_watch2.py (vmap/kcore watchers), README-session74.md. --- tools/guest-diag/wall2/gdbgap3.sh | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) create mode 100644 tools/guest-diag/wall2/gdbgap3.sh (limited to 'tools/guest-diag/wall2/gdbgap3.sh') diff --git a/tools/guest-diag/wall2/gdbgap3.sh b/tools/guest-diag/wall2/gdbgap3.sh new file mode 100644 index 0000000..bf19370 --- /dev/null +++ b/tools/guest-diag/wall2/gdbgap3.sh @@ -0,0 +1,28 @@ +#!/bin/bash +cd /tmp +(timeout 120 /tmp/vk_frame 1 64 64 5 /tmp 0 > /tmp/vk65.out 2>&1 &) +sleep 5 +PID=$(pgrep -x vk_frame | head -1) +cp /proc/$PID/maps /tmp/maps_d.txt +gdb -p $PID -batch -ex "set pagination off" -ex "bt 12" 2>&1 | grep -E "^#" > /tmp/bt_gap3.txt +python3 - <<'PY' +import re +maps=open('/tmp/maps_d.txt').read().splitlines() +segs=[] +for m in maps: + p=m.split() + if len(p)<6: continue + lo,hi=[int(x,16) for x in p[0].split('-')] + off=int(p[2],16) + segs.append((lo,hi,off,p[5])) +for line in open('/tmp/bt_gap3.txt'): + m=re.match(r'#(\d+)\s+0x([0-9a-f]+)', line) + if not m: continue + a=int(m.group(2),16) + for lo,hi,off,name in segs: + if lo<=a