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.
Regards,
Longman
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