Re: [PATCH] packfile: fix perf regression with many packs

[Jeff King <peff@peff.net>]

On Thu, Aug 13, 2026 at 09:35:49AM +0200, Patrick Steinhardt wrote:

> An alternative would be to use a hashmap here that tracks the packs that
> have already been added. It has the advantage that it also covers the
> `prepend()` operation and that callers don't have to be aware of this
> mechanism at all. Furthermore, moving preexisting entries to the back or
> front could become O(logn) if the list was doubly-linked. We do this
> operation quite often to re-sort entries in the list when looking up
> objects.

Don't we already use such a hashmap via packfile_store_add_pack() and
packfile_store_load_pack()? That comes from ec48540fe8 (packfile.c:
speed up loading lots of packfiles, 2019-11-27) and is how we know that
this "is_new" flag is true (otherwise we'd get duplicates during
"reprepare" operations).

-Peff