On Fri, Jun 14, 2013 at 5:20 PM, Octavian Purdila <octavian.purdila@xxxxxxxxx> wrote: > On Wed, Jun 12, 2013 at 10:40 PM, Zach Brown <zab@xxxxxxxxxx> wrote: >>> I've got an alternate approach for fixing this wart in lookup_ioctx()... >>> Instead of using an rbtree, just use the reserved id in the ring buffer >>> header to index an array pointing the ioctx. It's not finished yet, and >>> it needs to be tidied up, but is most of the way there. >> >> Yeah, that might work. >> >> Note that the patch wasn't using an rbtree, it was storing the pointer >> value in a *radix* which is why single lookups took so long. Presumably >> radix was used for RCU lookups. >> >> Your ring->id trick lets us use RCU with small ints instead of the >> context pointer. It might be worth using idr instead of rolling manual >> array code. It'd still be much faster than the list, but get rid of the >> large alloc, array walking, memcpy(), etc. >> > > I picked up Ben's patch and incorporated Zach's idea and the first > results look promising, as expected. I am going to do a full test with > the same workload I've used for rbtree and come back with the results > and the patch in a day or so. > Unfortunately, I still see performance degradation for the one ioctx case even when using IDR. I am using the same fio benchmark as before. -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
