Re: [PATCH v2 0/7] thread lazy_init_name_hash

> From: Jeff Hostetler <jeffhost@microsoft.com>
>
> Version 2 of this patch series addresses the coding
> style issues, compile errors in non-threaded builds,
> and updated API documentation.
>
>
> This patch series is a performance optimization for
> lazy_init_name_hash() in name-hash.c on very large
> repositories.
>
> This change allows lazy_init_name_hash() to optionally
> use multiple threads when building the the_index.dir_hash
> and the_index.name_hash hashmaps.  The original code path
> has been preserved and is used when the repo is small or
> the system does not have sufficient CPUs.
>
> A helper command (t/helper/test-lazy-init-name-hash) was
> created to demonstrate performance differences and validate
> output.  For example, use the '-p' option to compare both
> code paths on a large repo.
>
> During our testing on the Windows source tree (3.1M
> files, 500K folders, 450MB index) with an 8 (logical)
> core machine, we reduced the runtime of lazy_init_name_hash()
> from 1.4 to 0.27 seconds.
>
> This patch series replaces my earlier
>      * jh/memihash-opt (2017-02-17) 5 commits
> patch series.  This series is an improvement over the
> original proposal because it completely isolates the changes
> in name name-hash.c (rather than having parts in preload-index.c)
> and eliminates the need to update/invalidate precomputed hash
> values as cache_entries are changed.