From: Stefan Sperling <stsp@stsp.name>
Subject: Re: faster history traversal for 'got blame'
To: Martin Pieuchot <mpi@openbsd.org>, gameoftrees@openbsd.org
Date: Wed, 8 Jan 2020 09:32:50 +0100

On Wed, Jan 08, 2020 at 09:26:50AM +0100, Stefan Sperling wrote:
> Reading objects via privsep can be expensive.
> These caches avoid repeated decompression and copying of the same data.
> The repo format itself has no idea of caching.
> 
> To see the impact of caching, try a build with
> CFLAGS += -DGOT_NO_OBJ_CACHE

I lost my trail of thought there for a bit. The above doesn't actually
disable the pack index cache; it's separate from object caches.
But it's the same idea. Do not open/map, read, and close/unmap every pack
index file over and over, but keep some of them open/mapped and re-use them.