On 3/25/12 10:25 AM, Aubrey Li wrote:
On Mon, Mar 26, 2012 at 12:48 AM, Richard Elling
<richard.ell...@richardelling.com>  wrote:
This is the wrong forum for general purpose performance tuning. So I won't
continue this much farther.  Notice the huge number of icsw, that is a
symptom than locks.
  -- richard

thanks anyway, lock must be a problem. the scenario here is, apache
causes a bunch of stat()
syscall, which leads to a bunch of zfs vnode access, byond the normal
read/write operation.

The problem is, every zfs vnode access need the **same zfs root**
lock. When the number of
httpd processes and the corresponding kernel threads becomes large,
this root lock contention
becomes horrible. This situation does not occurs on linux.

Let me see if any others have a clue for me. Any suggestions will be
highly appreciated!


Is noatime turned on for all your zfs filesystems?
Have you tried the latest version of httpd?
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