On Fri, Sep 14, 2007 at 06:48:55AM +1000, Nick Piggin wrote: > On Thursday 13 September 2007 12:01, Nick Piggin wrote: > > On Thursday 13 September 2007 23:03, David Chinner wrote: > > > Then just do operations on directories with lots of files in them > > > (tens of thousands). Every directory operation will require at > > > least one vmap in this situation - e.g. a traversal will result in > > > lots and lots of blocks being read that will require vmap() for every > > > directory block read from disk and an unmap almost immediately > > > afterwards when the reference is dropped.... > > > > Ah, wow, thanks: I can reproduce it. > > OK, the vunmap batching code wipes your TLB flushing and IPIs off > the table. Diffstat below, but the TLB portions are here (besides that > _everything_ is probably lower due to less TLB misses caused by the > TLB flushing): > > -170 -99.4% sn2_send_IPI > -343 -100.0% sn_send_IPI_phys > -17911 -99.9% smp_call_function > > Total performance went up by 30% on a 64-way system (248 seconds to > 172 seconds to run parallel finds over different huge directories). Good start, Nick ;) > > 23012 54790.5% _read_lock > 9427 329.0% __get_vm_area_node > 5792 0.0% __find_vm_area > 1590 53000.0% __vunmap .... _read_lock? I though vmap() and vunmap() only took the vmlist_lock in write mode..... > Next I have some patches to scale the vmap locks and data > structures better, but they're not quite ready yet. This looks like it > should result in a further speedup of several times when combined > with the TLB flushing reductions here... Sounds promising - when you have patches that work, send them my way and I'll run some tests on them. Cheers, Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
