0ef169abb1
A persistent performance regression was discovered on
perf.golang.org/dashboard and this was narrowed down to the switch to
footers. Using allocation headers instead resolves the issue.
The benchmark results for allocation footers weren't realistic, because
they were performed on a machine with enough L3 cache that it completely
hid the additional cache miss introduced by allocation footers.
This means that in some corner cases the Go runtime may no longer
allocate 16-byte aligned memory. Note however that this property was
*mostly* incidental and never guaranteed in any documentation.
Allocation headers were tested widely within Google and no issues were
found, so we're fairly confident that this will not affect very many
users.
Nonetheless, by Hyrum's Law some code might depend on it. A follow-up
change will add a GODEBUG flag that ensures 16 byte alignment at the
potential cost of some additional memory use. Users experiencing both a
performance regression and an alignment issue can also disable the
GOEXPERIMENT at build time.
This reverts commit
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| SECURITY.md | ||
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