On Thu, Feb 21, 2013 at 11:13:27PM -0500, Waiman Long wrote: > On 02/21/2013 07:13 PM, Andi Kleen wrote: > >Dave Chinner<david@xxxxxxxxxxxxx> writes: > > > >>On Tue, Feb 19, 2013 at 01:50:55PM -0500, Waiman Long wrote: > >>>It was found that the Oracle database software issues a lot of call > >>>to the seq_path() kernel function which translates a (dentry, mnt) > >>>pair to an absolute path. The seq_path() function will eventually > >>>take the following two locks: > >>Nobody should be doing reverse dentry-to-name lookups in a quantity > >>sufficient for it to become a performance limiting factor. What is > >>the Oracle DB actually using this path for? > >Yes calling d_path frequently is usually a bug elsewhere. > >Is that through /proc ? > > > >-Andi > > > > > A sample strace of Oracle indicates that it opens a lot of /proc > filesystem files such as the stat, maps, etc many times while > running. Oracle has a very detailed system performance reporting > infrastructure in place to report almost all aspect of system > performance through its AWR reporting tool or the browser-base > enterprise manager. Maybe that is the reason why it is hitting this > performance bottleneck. That seems to me like an application problem - poking at what the kernel is doing via diagnostic interfaces so often that it gets in the way of the kernel actually doing stuff is not a problem the kernel can solve. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- 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
