On 8/15/07, Nicolas Pitre <nico@xxxxxxx> wrote: > On Wed, 15 Aug 2007, Jon Smirl wrote: > > > On 8/15/07, Martin Koegler <mkoegler@xxxxxxxxxxxxxxxxx> wrote: > > > git-pack-objects knows the order, in which it will use the objects. A > > > seperate thread could pre-read the next object and wait until the main > > > thread starts processing it. After the read is complete, another > > > thread could start computing the delta index. > > > > The hope is that the new adaptive read ahead code in the kernel will > > get this right and you won't need the second thread. Letting the > > kernel handle the read ahead will dynamically scale as other demands > > are made on the host. There's effectively only one read ahead cache in > > the system, only the kernel really knows how to divide it up between > > competing apps. > > No read ahead will ever help the delta search phase. Objects listed for > deltification against each other are sorted in a way that results in > reads from completely random location in the object store. > > Normally the delta search phase is so compute intensive that the read > shouldn't matter much. I agree, I am compute bound for 20 min, disk light occasionally dimly flickers. Besides, the main thread that is preparing the queue effectively functions as a read ahead thread. It will overlap with the compute bound delta searches. > > > Nicolas > -- Jon Smirl jonsmirl@xxxxxxxxx - To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
