Under O_DIRECT the expert *weights* are read with the direct fd (bypassing the
page cache), so a POSIX_FADV_WILLNEED on them warms pages the demand read never
consumes -- pure wasted readahead on the disk, the scarcest resource when
streaming. The .qs scales are ALWAYS read buffered (pread on the normal fd), so
keep their WILLNEED. This only changes hint-only PILOT (PILOT=1, PILOT_REAL=0)
combined with DIRECT=1; fadvise is advisory, so output is bit-identical.
Prepared, not yet measured: needs a real NVMe + full model to A/B cold-stream
tok/s (PILOT=1 DIRECT=1, with/without this patch, TEMP=0). See #441.
cdhdt
85107f8ce6