Re: [PATCH 6/7] delta_base_cache: use hashmap.h

Jeff King [off-list ref] writes:

So while the value for that case _isn't_ as good as the
optimal one measured above (which was 2048 entries), given
the bouncing I'm hesitant to suggest that 2048 is any kind
of optimum (not even for linux.git, let alone as a general
rule). The generic hashmap has the appeal that it drops the
number of tweakable numbers by one, which means we can focus
on tuning other elements, like the LRU strategy or the
core.deltaBaseCacheLimit setting.

And indeed, if we bump the cache limit to 1G (which is
probably silly for general use, but maybe something people
with big workstations would want to do), the linux.git log-S
time drops to 3m32s. That's something you really _can't_ do
easily with the static hash table, because the number of
entries needs to grow in proportion to the memory limit (so
2048 is almost certainly not going to be the right value
there).

This patch takes that direction, and drops the static hash
table entirely in favor of using the hashmap.h API.

Sounds very sensible.