An address-based build maps every readable registered range. A heap
range past APS5_HOST_IMPORT_MIB (or refused by the driver) was copied by
every such build: about 3200 ranges, 670 MiB and 500 ms per build on the
story-mode load, which then stalled. Such ranges are now served by
persistent host-cached mirrors, as the main image is, and the load
reaches its next failure.
- a heap mirror keeps no shadow; it keeps a write-tracking generation
per 64 KiB block and a build copies only the blocks stamped since. The
generation is stored by the copy, so a build that throws before it
leaves no block marked current with stale bytes
- the build gathers its heap mirrors, sorts them and collects each run
of adjacent ranges once (a collect costs about 4 us whatever its size;
~3000 mirrors took 16 ms per build, now about 3 ms)
- writable ranges are mirrored too: each build keeps the bytes its merged
written ranges held at upload and write-back stores only what the GPU
changed from them, so a CPU store made meanwhile stays; recorded work
writing a range completes before a refresh reads it
- the mirrors are limited by APS5_HEAP_MIRROR_MIB (24 GiB by default); a
mirror past it, or one whose buffer the driver refuses, stops the
process. Heap mirrors are not given to descriptor sub-ranges, image
mirror serials or reusable direct regions
- past APS5_ADDRESS_COPY_MAX_MIB (64 MiB by default) of committed bytes
still copied, a build stops the process, naming the largest ranges and
why each is copied (unreadable pages, an image mirror the driver
refused, a range outside the write-watched arena, mirrors disabled)
- a direct memory page mapped at several addresses is read-only in every
view while its range stays writable: copies, descriptor regions and
mirrors take every readable page, write-back stores the writable ones
and fails on a GPU change inside a read-only page instead of dropping it
- a store through the BDA table into a mirrored or copied range faults
as before (only writable ranges imported in place are writable there);
the fault now names the table range and that rule
- the BDA resource tests run with a storage range limit that holds the
fault buffer and cover a mirror's fill, reuse, per-block refill, an
interrupted refresh, a descriptor store beside a concurrent CPU store,
and the copy limit
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
119560206d