Re: redo copy latch

From: Kristiaan Johan Kolk <akolk_at_us.oracle.com>
Date: Thu, 12 Nov 1998 12:16:16 -0800
Message-ID: <364B4210.1958497@us.oracle.com>

My guess is that this potential performance problem is very small compared to other issues that you may face:

step 1:
- look for 'latch free' in v$system_event, how much of the time_waited is really part of the overall wait time

step 2:
- look at v$latch to find the redo copy latch and the number of sleeps there are. (compare this to waits for latch free in v$system_event)

step 3:
- now you can determine how important these latch misses are for the performance.

Anjo Kolk
(I work for Oracle but I speak for my self).

daud11_at_my-dejanews.com wrote:

> Hi
>
> The ratio of MISSES to GETS for redo copy latch is more than 90% for my
> oracle database. Does that mean that there is a problem with contention for
> the redo copy latch? Should I increase the parameter LOG_SIMULTANEOUS_COPIES
> to twice the number of CPU? Currently LOG_SIMULTANEOUS_COPIES = no of CPU
> (2).
>
> Some explanations from you guys out there will be appreciated.
>
> thanks
> Daud11
>
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Received on Thu Nov 12 1998 - 14:16:16 CST