Johannes Schindelin wrote: > On Wed, 22 Mar 2017, Jonathan Nieder wrote: > > Johannes Schindelin wrote:
>>> As to the default of seriously slowing down all SHA-1 computations: >>> since you made that the default, at compile time, with no way to turn >>> on the faster computation, this will have a major, negative impact. >>> Are you really, really sure you want to do that? >>> >>> I thought that it was obvious that we would have at least a runtime >>> option to lessen the load. >> >> It's not obvious to me. I agree that the DC_SHA1 case can be sped up, >> e.g. by turning off the collision detection for sha1 calculations that >> are not part of fetching, receiving a push, or running fsck. > > And in those cases, using OpenSSL instead is *even* faster. [...] > The index is 300MB. If you have to experience a sudden drop in performance > of `git add`, even by "only" 30%, relative to OpenSSL, it is very > noticeable. It is painful. [...] > It gets even worse when it comes to fetching, let alone cloning. [...] > And by "switching collision detection off", I of course refer to *not* > using SHA1DC's routines at all, but what would have been used originally, > in Git for Windows' case: (hardware-accelerated) OpenSSL. > > Did I manage to clarify the problem? Yes. Thank you for explaining. Sincerely, Jonathan
