comparison mercurial/configitems.toml @ 51108:0250e45040f1

revlog: add a small cache of unfiltered chunk

This can provides a massive boost to the reading of multiple revision and the
computation of a valid delta chain.

This greatly help operation like `hg log --patch`, delta computation (helping
pull/unbundle), linkrev adjustment (helping copy tracing).

A first round of benchmark for `hg log --patch --limit 1000` shows improvement
in the 10-20% range on "small" repository like pypy or mercurial and large
improvements (about 33%) for more complex ones like netbeans and mozilla's.

These speeds up are consistent with the improvement to `hg pull` (from a server
sending poor deltas) I saw benchmarking this last year. Further benchmark will
be run during the freeze.

I added some configuration in the experimental space to be able to further test
the effect of various tuning for now. This feature should fit well in the
"usage/resource profile" configuration that we should land next cycle.

When it does not provides a benefit the overhead of the cache seem to be around
2%, a small price for the big improvement. In addition I believe we could shave
most of this overhead with a more efficent lru implementation.

51107:c2d2e5b65def

name = "sparse-read.min-gap-size"
default = "65K"

[[items]]
section = "experimental"
name = "stream-v3"
default = false

[[items]]
section = "experimental"

51108:0250e45040f1

name = "sparse-read.min-gap-size"
default = "65K"

[[items]]
section = "experimental"
name = "revlog.uncompressed-cache.enabled"
default = true
experimental = true
documentation = """Enable some caching of uncompressed chunk, greatly boosting
performance at the cost of memory usage."""

[[items]]
section = "experimental"
name = "revlog.uncompressed-cache.factor"
default = 4
experimental = true
documentation = """The size of the cache compared to the largest revision seen."""

[[items]]
section = "experimental"
name = "revlog.uncompressed-cache.count"
default = 10000
experimental = true
documentation = """The number of chunk cached."""

[[items]]
section = "experimental"
name = "stream-v3"
default = false

[[items]]
section = "experimental"