On Tue, 2010-07-20 at 13:12 +1000, Nick Piggin wrote: > On Thu, Jul 08, 2010 at 04:56:27PM +0800, Zhang, Yanmin wrote: > > Nick, > > > > I work with Andi Kleen and Tim to investigate some scalability issues. > > > > Andi gave me a pointer at: > > http://thread.gmane.org/gmane.linux.kernel/1002380/focus=42284 > > > > Where can I get your latest patches? It's better if I could get patch tarball. > > > > Thanks, > > Yanmin > > > > Hi Yanmin, > > Sorry for the delay. I have a git tree now, and it has been through > some tress testing. > > http://git.kernel.org/?p=linux/kernel/git/npiggin/linux-npiggin.git > > I would be very interested to know if you encounter problems or are > able to generate any benchmark numbers. Nick, We ran lots of benchmarks on many machines. Below is something to share with you. Improvement: 1) We get about 30% improvement with kbuild workload on Nehalem machines. It's hard to improve kbuild performance. Your tree does. Issues: 1) Compiling fails on a couple of file systems, such like CONFIG_ISO9660_FS=y. 2) dbenchthreads has about 50% regression. We connect a JBOD of 12 disks to a machine. Start 4 dbench threads per disk. We run the workload under a regular user account. If we run it under root account, we get 22% improvement instead of regression. The root cause is ACL checking. With your patch, do_path_lookup firstly goes through rcu steps which including a exec permission checking. With ACL, the __exec_permission always fails. Then a later nameidata_drop_rcu often fails as dentry->d_seq is changed. With root account, it doesn't happen. We mount the working devices under /mnt/stp/XXX. /mnt is of root user. So the exec permission check is ok. I remount all file systems on the testing path with noacl option, and get the similar results like under root account. 3) aim7 has about 40% regression on Nehalem EX 4-socket machine. The root cause is the same thing like 2). Other benchmarks' results have no improvement or regression. Yanmin -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>