On 8/13/2018 12:25 PM, Duy Nguyen wrote:
On Mon, Aug 13, 2018 at 6:05 PM Ben Peart <peartben@xxxxxxxxx> wrote:
I was part way through writing a patch that would copy the valid parts
of the cache-tree from the source index to the dest index
Yeah sorry about that. I make bad judgements all the time, unfortunately.
If it's sort of working though, please post to the list anyway to
archive it. Who knows, some time down the road we might actually need
it again.
I run some tests on a large repo and the results look very promising.
base new diff % saved
0.55 0.52 0.02 4.32% s: read cache .git/index
0.31 0.30 0.01 2.98% s: initialize name hash
0.03 0.02 0.00 9.98% s: preload index
0.09 0.09 0.00 4.86% s: refresh index
5.93 1.19 4.74 79.95% s: traverse_trees
0.12 0.13 -0.01 -4.15% s: check_updates
2.14 0.00 2.14 100.00% s: cache_tree_update
10.63 4.29 6.33 59.59% s: unpack_trees
There's a big gap here, I think. unpack_trees() takes 4s but the sum
of traverse_trees, check_updates and cache_tree_update is 1.5s top. I
guess that's sparse checkout and stuff? It's either that or there's
another big hidden thing we should pay attention to ;-)
Yes, there are additional costs associated with the sparse-checkout and
excludes logic. We've sped that up significantly by converting it to a
hashmap but it still has measurable cost as we have to compute the hash
of the cache entry name before looking it up.
Name Inc % Inc
+ git!unpack_trees 50.9 4,575
|+ git!clear_ce_flags_1 16.5 1,479
||+ git!is_included_in_virtualfilesystem 15.9 1,430
|| + git!check_includes_hashmap 15.8 1,418
|+ git!traverse_trees 16.3 1,468
|+ git!cache_tree_fully_valid 11.7 1,055
|+ git!check_updates 1.9 169
|+ git!discard_index 1.8 162
|+ git!apply_sparse_checkout 0.2 15
|+ git!next_cache_entry 0.0 3
