From: Linus Torvalds Date: Thu, 06 Dec 2007 18:35:22 GMT Subject: Re: Git and GCC Message-ID: In-Reply-To: <20071206173946.GA10845@sigill.intra.peff.net> On Thu, 6 Dec 2007, Jeff King wrote: > > What is really disappointing is that we saved only about 20% of the > time. I didn't sit around watching the stages, but my guess is that we > spent a long time in the single threaded "writing objects" stage with a > thrashing delta cache. I don't think you spent all that much time writing the objects. That part isn't very intensive, it's mostly about the IO. I suspect you may simply be dominated by memory-throughput issues. The delta matching doesn't cache all that well, and using two or more cores isn't going to help all that much if they are largely waiting for memory (and quite possibly also perhaps fighting each other for a shared cache? Is this a Core 2 with the shared L2?) Linus