Re: KCL gc element parent latch

From: Tanel Poder <>
Date: Wed, 16 Dec 2009 19:16:01 +0200
Message-ID: <>

GC operations may require changes to PCM locks / lock elements. The lock element array (V$GC_ELEMENT) is protected by gc element latches... so if you have lots of GC ops, these latches will be used. *Fix the GC traffic and the latching problem will go away.*

How significant % of your sessions response time is spent waiting for this latch?

If you see significant waits for that latch, you can run latchprofX to gain undersanding who are the main holders of these latches and which kernel functions cause the latches to be held the most etc:


On Wed, Dec 16, 2009 at 4:27 AM, Rajesh Rao <> wrote:

> RAC. Looking to get more insight into this latch as I see seek
> to troubleshoot and check for co-relation to an issue with sessions
> experiencing “gc cr request” waits. Especially, what causes sessions to wait
> on this latch?
> Regards
> Raj
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Tanel Poder

Received on Wed Dec 16 2009 - 11:16:01 CST

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