Re: perplexing performance on AIX
- From: "John Smith" <john40855@xxxxxxxxx>
- To: "David Barbour" <david.barbour1@xxxxxxxxx>
- Date: Tue, 6 May 2008 17:04:33 -0500
JFS2 file system mounted with CIO
OS: 5300-05-06
FilesystemIO_options=setall
I dont know what HBA's are being used.
Top five timed events:
~~~~~~~~~~~~~~~~~~ wait Call
Event Waits Time (s) (ms) Time Wait
Class
------------------------------ ------------ ----------- ------ ------
----------
PX Deq Credit: send blkd 59,803 6,103 102 79.1
Other
CPU time 515 7.0
direct path read 23,833 292 11 4.0 User
I/O
db file sequential read 139,499 225 2 3.1 User
I/O
direct path read temp 7,632 98 13 1.4 User
I/O
-------------------------------------------------------------
On Tue, May 6, 2008 at 4:50 PM, David Barbour <david.barbour1@xxxxxxxxx>
wrote:
> John,
>
> What version of AIX, including maintenance level. What is your
> filesystemio_options parameter? What HBAs are you using? Raw, or journaled
> filesystems? JFS2? How are they mounted?
>
> What do you see with iostat?
>
> On Tue, May 6, 2008 at 4:32 PM, John Smith <john40855@xxxxxxxxx> wrote:
>
> > Not that I want to discourage any potential comedians, but I do
> > understand the concept of idle waits. However, the wait event seems
> > excessive, (its larger than any other timed event on the system, to include
> > CPU time), which makes me suspect that there is a problem.
> >
> >
> > On Tue, May 6, 2008 at 3:11 PM, Baumgartel, Paul <
> > paul.baumgartel@xxxxxxxxxxxxxxxxx> wrote:
> >
> > > On Tue, May 6, 2008 at 2:21 PM, Allen, Brandon <
> > > Brandon.Allen@xxxxxxxxxxx> wrote:
> > >
> > > > If you disabled parallellism, you couldn't get PX wait events. You
> > > > might want to try with DOP of 1. I'd also verify CIO is being used if
> > > > you
> > > > aren't sure.
> > > >
> > >
> > >
> > > Reminds me of the old Henny Youngman joke: "I went to the doctor. I
> > > said 'Doc, it hurts when I do this.' He said 'Don't do that.'"
> > >
> > > *Paul Baumgartel*
> > > *CREDIT SUISSE*
> > > Information Technology
> > > Prime Services Databases Americas
> > > One Madison Avenue
> > > New York, NY 10010
> > > USA
> > > Phone 212.538.1143
> > > paul.baumgartel@xxxxxxxxxxxxxxxxx
> > > www.credit-suisse.com
> > >
> > >
> > > ------------------------------
> > > *From:* oracle-l-bounce@xxxxxxxxxxxxx [mailto:
> > > oracle-l-bounce@xxxxxxxxxxxxx] *On Behalf Of *John Smith
> > > *Sent:* Tuesday, May 06, 2008 3:29 PM
> > > *To:* Allen, Brandon; oracle-l@xxxxxxxxxxxxx
> > > *Subject:* Re: perplexing performance on AIX
> > >
> > > We really want to be able to use parallel.
> > >
> > >
> > > > ------------------------------
> > > > *From:* John Smith [mailto:john40855@xxxxxxxxx]
> > > > *Sent:* Tuesday, May 06, 2008 11:57 AM
> > > > *To:* Allen, Brandon
> > > > *Subject:* Re: perplexing performance on AIX
> > > >
> > > > Yes, we tried decreasing the DOP. Didnt really affect the wait
> > > > event. I am pretty sure the drives are already mounted w/ CIO. At
> > > > least
> > > > they are supposed to be.
> > > >
> > > > On Tue, May 6, 2008 at 1:20 PM, Allen, Brandon <
> > > > Brandon.Allen@xxxxxxxxxxx> wrote:
> > > >
> > > > > Have you tried decreasing the degree of parallelism (or maybe
> > > > > even disabling it) to see if that helps? Sometimes too
> > > > > muchparallelism is
> > > > > a bad thing.
> > > > >
> > > > > You might also want to consider using concurrent IO if you're not
> > > > > already.
> > > > >
> > > > > Regards,
> > > > > Brandon
> > > > >
> > > > >
> > > > >
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