Re: [PATCH] Don't search files with an unset "grep" attribute

Jeff King [off-list ref] writes:

Part of the problem, I suspect, is that the attribute lookup code is
optimized for locality. We only unwind as much of the stack as we need,
so looking at "foo/bar/baz.c" after "foo/bar/bleep.c" is much cheaper
than looking at "some/other/directory.c". But with threaded grep, that
locality is likely lost, as we are mixing up attribute requests from
different threads.

Given that binary lookup means we need every file's gitattribute, it
might be better to look them up serially at the beginning of the
program, and then pass the resulting userdiff driver to grep_buffer
along with each path.

Yeah, that was my impression when the performance of threaded grep was
discussed, which was before this "let's honor binary attribute".