Whether a boot restores a stored heap instead of booting the kernel. ON, with HEAP_SNAPSHOT=0
to turn it off.
It shipped opt-in with a precondition written into ensurePhp(): the standalone restore probe ran
in one process with no Durable Object and no vrzno bridge in the image, so "until a host call is
shown to round-trip through a restored heap, this must not be on by default." That precondition is
now met -- /heap?op=bridge forces PHP to reach cfwStats through vrzno_env() on a restored
image and it round-trips with 3 handles replayed and the digest equal, and an install then runs on
that kernel and lands.
Priced before flipping it, because the storage is not free: 31,784,960 bytes across 159 rows per
site, plus a 5,993 ms one-off to take the snapshot. What it buys is 2,310 ms (fast mode) to
3,578 ms (slow mode) off every install, n=8 per arm, present in BOTH modes of a bimodal
population -- which is what makes it a result rather than an artefact of which mode was sampled.
Whether a boot restores a stored heap instead of booting the kernel. ON, with
HEAP_SNAPSHOT=0to turn it off.It shipped opt-in with a precondition written into
ensurePhp(): the standalone restore probe ran in one process with no Durable Object and no vrzno bridge in the image, so "until a host call is shown to round-trip through a restored heap, this must not be on by default." That precondition is now met --/heap?op=bridgeforces PHP to reachcfwStatsthroughvrzno_env()on a restored image and it round-trips with 3 handles replayed and the digest equal, and an install then runs on that kernel and lands.Priced before flipping it, because the storage is not free: 31,784,960 bytes across 159 rows per site, plus a 5,993 ms one-off to take the snapshot. What it buys is 2,310 ms (fast mode) to 3,578 ms (slow mode) off every install, n=8 per arm, present in BOTH modes of a bimodal population -- which is what makes it a result rather than an artefact of which mode was sampled.