On Fri, Mar 24, 2017 at 01:27:51PM +0000, git@xxxxxxxxxxxxxxxxx wrote: > From: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx> > > Teash do_read_index() in read-cache.c to call verify_hdr() > in a background thread while the forground thread parses > the index and builds the_index. > > This is a performance optimization to reduce the overall > time required to get the index into memory. > > Testing on Windows (using the OpenSSL SHA1 routine) showed > that parsing the index and computing the SHA1 take almost > equal time, so this patch effectively reduces the startup > time by 1/2. Have you considered just skipping the sha1 check on read (possibly with an option)? Its purpose is to detect disk bit-rot. Checking it for every single operation may be a bit excessive, especially because it gets rewritten a lot. Nobody really cared until now because they don't have index files that are hundreds of megabytes. -Peff