Hi Jon, Increasing LGWR priority would only help if it was currently starving for CPU / or waiting too long in the CPU runqueue... Unfortunately on Linux there's no easy way to measure this directly. If your load is low (let's say only 10 on a 32 CPU machine) then I'd expect that LGWR priority change isn't going to help much. However, I don't like to fix a problem first and then see whether the problem existed in first place (trial and error), that's why I asked for extra information / hard evidence in form of LGWR's snapper output ... Tanel. On Tue, May 1, 2012 at 6:19 PM, CRISLER, JON A <JC1706@xxxxxxx> wrote: > Red Hat Linux 5. We have async DG running but Real Time apply is also > configured, and redo logs are mirrored. I believe LGWR is not starved for > CPU given the overall conditions for the system, but I am finding some info > that putting lgwr in a real-time OS priority would be a good thing.**** > > ** ** > > The default for _*high_priority*_processes is LMS*|VKTM but I have seen > some Metalink notes about adding LGWR. I also saw a blog post that > mentioned you discussed setting this parameter at a HOTSOS seminar, and > this is something we are considering. Given all the CPU power in this > server, and all the LMS processes, I don?t this would pose a problem.**** > > ** ** > > alter system set "_high_priority_processes"='LMS*|VKTM|LGWR' scope=spfile > sid='*';**** > > **** > > ** ** > > ** ** > > *From:* tanel@xxxxxxxxxx [mailto:tanel@xxxxxxxxxx] *On Behalf Of *Tanel > Poder > *Sent:* Monday, April 30, 2012 6:21 PM > > *To:* CRISLER, JON A > *Cc:* oracle-l > *Subject:* Re: log buffer size and log file syncs**** > > ** ** > > Which OS are you on? If it happens to be Solaris, then prstat -mLp *PID*would > show the scheduling latency for LGWR. This would help to find out > whether LGWR is CPU starved or not.... what load averages do you have?**** > > ** ** > > Also, what does snapper say when ran on LGWR? If you have synchronous DG > for example, then LGWR would wait for the LNS ack too in addition to the > log file parallel write wait, before returning OK back to the committing > session ...**** > > ** ** > > Tanel.**** > > On Mon, Apr 30, 2012 at 5:56 PM, CRISLER, JON A <JC1706@xxxxxxx> wrote:*** > * > > Interesting thoughts Tanel: in this case of this specific app, the > majority of the work is made of up small commits to a handful of tables on > a 6 node RAC cluster. I/O times are generally quite good, and with 32 > cores per node the CPU and load average is very low. Its 11gR1 ? I was > wondering if some of the tweaks to put LGWR at ?real time? priority that > are mentioned for 10g also apply to 11g.**** > > ** ** > -- //www.freelists.org/webpage/oracle-l