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). 23012 54790.5% _read_lock 9427 329.0% __get_vm_area_node 5792 0.0% __find_vm_area 1590 53000.0% __vunmap 107 26.0% _spin_lock 74 119.4% _xfs_buf_find 58 0.0% __unmap_kernel_range 53 36.6% kmem_zone_alloc -129 -100.0% pio_phys_write_mmr -144 -100.0% unmap_kernel_range -170 -99.4% sn2_send_IPI -233 -59.1% kfree -266 -100.0% find_next_bit -343 -100.0% sn_send_IPI_phys -564 -19.9% xfs_iget_core -1946 -100.0% remove_vm_area -17911 -99.9% smp_call_function -62726 -7.2% _write_lock -438360 -64.2% default_idle -482631 -30.4% total 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... - 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