compat_pread mapped every non-EOF ReadFile failure to EIO, so the field report
was always the same three words: "Input/output error". #307 then burned three
rounds of guessing across three people — storage? contention? alignment? —
because the actual GetLastError code never appeared anywhere.
compat_pread now stashes the code in a per-thread slot and pread_full appends
it to the failure line:
pread qs: Input/output error (off 780592, 0/8192 bytes, WinErr=1450)
That one number is the difference between "insufficient system resources"
(1450 -> memory pressure), "sharing violation" (32 -> AV interference),
"device not ready" (21 -> the T: drive itself) and a dozen other distinct
diagnoses. Diagnostic only: no behavior change, no retry policy — that
discussion lives in #361 and should be settled AFTER the first report tells
us which error we are actually retrying.
Linux path untouched byte-for-byte; the Windows compile is certified by the
check.yml MSYS2 job.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Cut Windows decode disk I/O from 2.06s/tok to 1.70s/tok (budget=4), meeting the
<=2s/tok target. Two changes on the pread expert-load path:
1. compat.h: replace the posix_fadvise no-op with a real WILLNEED cache-warmer
(overlapped ReadFile into a scratch buffer -> populates the standby page cache
so the later synchronous pread faults from RAM). Re-arms the existing
expert_prefetch/PILOT/next-block prefetch chain on Windows. DONTNEED stays a
no-op (matches macOS; Windows standby-list trimming self-regulates).
Measured: hit rate 16.4% -> 27.6%.
2. glm.c: flip PIPE (async expert-load thread pool) from default OFF to default ON
on Windows. Dispatches expert pread onto worker threads so loads overlap the
matmul, instead of blocking serial load-then-compute. PIPE=0 opts out.
Measured: expert-disk 65.9s -> 54.3s (-18%).
Also adds compat_fadvise assertions to tests/test_compat_direct.c (data integrity
after cache-warmer, safe no-op on bad fd / non-WILLNEED).
mmap (CreateFileMapping/MapViewOfFile) was implemented and tested at length but
reverted: it regressed on Windows (RSS bloat from touched mapped pages collapsed
the expert cache via ullAvailPhys — a fundamental Windows-vs-Linux difference).
Full findings + the dead-end analysis recorded in issue_diskio.md.
* win: direct I/O via FILE_FLAG_NO_BUFFERING + compat_fsize + VirtualLock primitives
compat_open_direct() gives Windows the O_DIRECT twin fd st.h already uses
on Linux/macOS: FILE_FLAG_NO_BUFFERING, same 4K-alignment contract as
O_DIRECT (the engine's DIRECT=1 path already aligns offset/len and slabs
are posix_memalign'd).
Measured on GLM-5.2 744B int4, Ryzen 9 9950X3D / 126 GB / PCIe4 NVMe
(5.8 GB/s at the engine's 19MBx8T pattern), Windows 11, MinGW GCC 16.1,
32-token greedy runs at --topp 0.7, 40 GB pin, current dev HEAD:
buffered: 0.38 tok/s (expert-disk dominates)
DIRECT=1: 0.56 tok/s (1.47x) — byte-identical greedy output vs buffered
compat_fsize() (GetFileSizeEx): CRT lseek(SEEK_END) returns -1 on
NO_BUFFERING fds (measured on UCRT); iobench uses it and gains a
NO_BUFFERING branch so disk numbers are comparable across platforms.
compat_mlock/compat_munlock: VirtualLock with working-set growth (bare
VirtualLock caps at the default working-set minimum, a few hundred KB).
Wired into the engine in the next commit.
tests/test_compat_direct.c covers the alignment contract, data integrity,
fsize on both fd kinds; skips cleanly off Windows.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
* win: wire VirtualLock into mem_wire, munlock pairing in expert_host_release
MLOCK=1 was a silent no-op on Windows: pinned experts could be paged out
by working-set trimming under memory pressure. mem_wire now uses
compat_mlock (VirtualLock + working-set growth); expert_host_release
unlocks before freeing, mirroring the POSIX branch.
Validated: 39.6 GB pin wired in 17s on a 126 GB machine, zero failures;
TF oracle 32/32 with MLOCK=1.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
* cuda: thread-local current-device cache in select_ctx
cudaSetDevice on every call is expensive when the serial expert loop
alternates devices. Measured on RTX 5090 + RTX 4090 (Windows, DLL
backend, pre-#68 dispatch): expert-matmul 14.3s -> 25.4s per 32 tokens
going from 1 to 2 devices, entirely per-call context switching. The
current device is per-thread in the CUDA runtime, so a thread_local
cache skips redundant switches; multi-GPU expert serving becomes
positive-scaling instead of negative.
Kernel suite passes on sm_120 + sm_89; TF oracle 32/32 dual-GPU.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---------
Co-authored-by: olorin <io@zyphyr.co>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
JustVugg