On 3/27/2017 6:45 PM, Jeff King wrote:
On Mon, Mar 27, 2017 at 09:09:37PM +0000, git@xxxxxxxxxxxxxxxxx wrote:From: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx> Version 2 of this patch series simplifies this to just turn off the hash verification. Independent comments from Linus and Peff suggested that we could just turn this off and not worry about it. So I've updated this patch to do that. I added a global variable to allow the original code path to be used. I also added a t/helper command to demonstrate the differences. On the Linux repo, the effect is rather trivial: $ ~/work/gfw/t/helper/test-skip-verify-index -c 3 0.029884 0 [cache_nr 57994] 0.031035 0 [cache_nr 57994] 0.024308 0 [cache_nr 57994] 0.028409 0 avg 0.018359 1 [cache_nr 57994] 0.017025 1 [cache_nr 57994] 0.011087 1 [cache_nr 57994] 0.015490 1 avg On my Windows source tree (450MB index), I'm seeing a savings of 0.6 seconds -- read_index() went from 1.2 to 0.6 seconds.Very satisfying. I assume that was with OpenSSL as the SHA-1 implementation (sha1dc would have been much slower on 450MB, I think). -Peff
Yes, this was with the OpenSSL SHA-1 code in a GfW build. I haven't played with the sha1dc code yet. $ $/work/gh_gfw/t/helper/test-skip-verify-index.exe -c 5 1.276485 0 [cache_nr 3077831] 1.261164 0 [cache_nr 3077831] 1.256012 0 [cache_nr 3077831] 1.261411 0 [cache_nr 3077831] 1.266174 0 [cache_nr 3077831] 1.264249 0 avg 0.672057 1 [cache_nr 3077831] 0.666968 1 [cache_nr 3077831] 0.668725 1 [cache_nr 3077831] 0.675879 1 [cache_nr 3077831] 0.670213 1 [cache_nr 3077831] 0.670768 1 avg Jeff