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	<title>Latch, mutex and beyond</title>
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	<link>http://andreynikolaev.wordpress.com</link>
	<description>Yet another look on Oracle latch performance</description>
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		<title>Latch, mutex and beyond</title>
		<link>http://andreynikolaev.wordpress.com</link>
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	<atom:link rel="search" type="application/opensearchdescription+xml" href="http://andreynikolaev.wordpress.com/osd.xml" title="Latch, mutex and beyond" />
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		<item>
		<title>Latch Timescales</title>
		<link>http://andreynikolaev.wordpress.com/2011/12/22/latch-timescales/</link>
		<comments>http://andreynikolaev.wordpress.com/2011/12/22/latch-timescales/#comments</comments>
		<pubDate>Thu, 22 Dec 2011 12:44:28 +0000</pubDate>
		<dc:creator>andreynikolaev</dc:creator>
				<category><![CDATA[Latch]]></category>
		<category><![CDATA[Theory]]></category>
		<category><![CDATA[_spin_count]]></category>

		<guid isPermaLink="false">http://andreynikolaev.wordpress.com/?p=3681</guid>
		<description><![CDATA[To compare old and new latch mechanisms, I found useful the following illustration. Since it is hard for us, humans, to visualize milli- and microseconds, imagine “time microscope” that zooms in timed events one million times. Alternatively, just imagine contemporary Oracle software running on 1950th style hardware. Such microscope will magnify the microsecond to second. [...]<img alt="" border="0" src="http://stats.wordpress.com/b.gif?host=andreynikolaev.wordpress.com&amp;blog=8081483&amp;post=3681&amp;subd=andreynikolaev&amp;ref=&amp;feed=1" width="1" height="1" />]]></description>
		<wfw:commentRss>http://andreynikolaev.wordpress.com/2011/12/22/latch-timescales/feed/</wfw:commentRss>
		<slash:comments>2</slash:comments>
	
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			<media:title type="html">AndreyNikolaev</media:title>
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	</item>
		<item>
		<title>UKOUG 2011</title>
		<link>http://andreynikolaev.wordpress.com/2011/11/24/ukoug-2011/</link>
		<comments>http://andreynikolaev.wordpress.com/2011/11/24/ukoug-2011/#comments</comments>
		<pubDate>Thu, 24 Nov 2011 19:35:52 +0000</pubDate>
		<dc:creator>andreynikolaev</dc:creator>
				<category><![CDATA[Conference]]></category>

		<guid isPermaLink="false">http://andreynikolaev.wordpress.com/?p=3667</guid>
		<description><![CDATA[I will be speaking about latches at UK Oracle User Group Conference 2011. It will be my first visit to this extraordinary conference and UK. Hopefully see you there!<img alt="" border="0" src="http://stats.wordpress.com/b.gif?host=andreynikolaev.wordpress.com&amp;blog=8081483&amp;post=3667&amp;subd=andreynikolaev&amp;ref=&amp;feed=1" width="1" height="1" />]]></description>
		<wfw:commentRss>http://andreynikolaev.wordpress.com/2011/11/24/ukoug-2011/feed/</wfw:commentRss>
		<slash:comments>1</slash:comments>
	
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			<media:title type="html">AndreyNikolaev</media:title>
		</media:content>

		<media:content url="http://www.ukoug.org/public/images/i-am-speaking-at-ukoug-2011-xsmall-copy.gif" medium="image">
			<media:title type="html"> </media:title>
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	</item>
		<item>
		<title>Mutex waits. Part II. &#8220;Cursor: Pin S&#8221; in Oracle 11.2  _mutex_wait_scheme=0. Steps out of shadow.</title>
		<link>http://andreynikolaev.wordpress.com/2011/10/25/mutex-waits-part-ii-cursor-pin-s-in-oracle-11-2-_mutex_wait_scheme0-steps-out-of-shadow/</link>
		<comments>http://andreynikolaev.wordpress.com/2011/10/25/mutex-waits-part-ii-cursor-pin-s-in-oracle-11-2-_mutex_wait_scheme0-steps-out-of-shadow/#comments</comments>
		<pubDate>Tue, 25 Oct 2011 16:23:12 +0000</pubDate>
		<dc:creator>andreynikolaev</dc:creator>
				<category><![CDATA[11.2]]></category>
		<category><![CDATA[Contention]]></category>
		<category><![CDATA[DTrace]]></category>
		<category><![CDATA[Instrumentation]]></category>
		<category><![CDATA[Mutex]]></category>
		<category><![CDATA[OS tuning]]></category>
		<category><![CDATA[Patches]]></category>

		<guid isPermaLink="false">http://andreynikolaev.wordpress.com/?p=3137</guid>
		<description><![CDATA[I would like to describe how Oracle versions 11.2.0.1-11.2.0.2.1 waited for mutexes. This algorithm also appears to be used in post-11.2.0.2.2 PSUs and new 11.2.0.3 patchset as _mutex_wait_scheme=0. My previous post demonstrated that before version 11.2: &#8220;Cursor: pin S&#8221; was pure wait for CPU. Long &#8220;cursor: pin S&#8221; waits indicated CPU starvation. Mutex contention was [...]<img alt="" border="0" src="http://stats.wordpress.com/b.gif?host=andreynikolaev.wordpress.com&amp;blog=8081483&amp;post=3137&amp;subd=andreynikolaev&amp;ref=&amp;feed=1" width="1" height="1" />]]></description>
		<wfw:commentRss>http://andreynikolaev.wordpress.com/2011/10/25/mutex-waits-part-ii-cursor-pin-s-in-oracle-11-2-_mutex_wait_scheme0-steps-out-of-shadow/feed/</wfw:commentRss>
		<slash:comments>4</slash:comments>
	
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			<media:title type="html">AndreyNikolaev</media:title>
		</media:content>

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			<media:title type="html">mutime2</media:title>
		</media:content>

		<media:content url="http://andreynikolaev.files.wordpress.com/2011/10/mutex_0_tps-e1319236890180.jpg" medium="image">
			<media:title type="html">mutex_0_tps</media:title>
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	</item>
		<item>
		<title>Mutex waits. Part 1. “Cursor: Pin S” in Oracle 10.2-11.1. Invisible and aggressive.</title>
		<link>http://andreynikolaev.wordpress.com/2011/07/09/mutex-waits-part-1-%e2%80%9ccursor-pin-s%e2%80%9d-in-oracle-10-2-11-1-invisible-and-aggressive/</link>
		<comments>http://andreynikolaev.wordpress.com/2011/07/09/mutex-waits-part-1-%e2%80%9ccursor-pin-s%e2%80%9d-in-oracle-10-2-11-1-invisible-and-aggressive/#comments</comments>
		<pubDate>Sat, 09 Jul 2011 13:18:50 +0000</pubDate>
		<dc:creator>andreynikolaev</dc:creator>
				<category><![CDATA[Contention]]></category>
		<category><![CDATA[History]]></category>
		<category><![CDATA[Instrumentation]]></category>
		<category><![CDATA[Mutex]]></category>
		<category><![CDATA[Patches]]></category>
		<category><![CDATA[Spinlock]]></category>

		<guid isPermaLink="false">http://andreynikolaev.wordpress.com/?p=2967</guid>
		<description><![CDATA[Oracle KGX mutexes appeared more than 7 years ago. However, mutex waits are still obscure. Oracle Documentation provided only brief description of mutex wait events without any information about wait durations and timeouts. Look at the following timeline: In 2005 mutexes were introduced with Oracle 10.2.0.2 patchset. Documentation states that “cursor: pin S” wait event [...]<img alt="" border="0" src="http://stats.wordpress.com/b.gif?host=andreynikolaev.wordpress.com&amp;blog=8081483&amp;post=2967&amp;subd=andreynikolaev&amp;ref=&amp;feed=1" width="1" height="1" />]]></description>
		<wfw:commentRss>http://andreynikolaev.wordpress.com/2011/07/09/mutex-waits-part-1-%e2%80%9ccursor-pin-s%e2%80%9d-in-oracle-10-2-11-1-invisible-and-aggressive/feed/</wfw:commentRss>
		<slash:comments>12</slash:comments>
	
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			<media:title type="html">AndreyNikolaev</media:title>
		</media:content>
	</item>
		<item>
		<title>MEDIAS-2011</title>
		<link>http://andreynikolaev.wordpress.com/2011/05/22/medias-2011/</link>
		<comments>http://andreynikolaev.wordpress.com/2011/05/22/medias-2011/#comments</comments>
		<pubDate>Sun, 22 May 2011 13:56:05 +0000</pubDate>
		<dc:creator>andreynikolaev</dc:creator>
				<category><![CDATA[Conference]]></category>
		<category><![CDATA[DTrace]]></category>
		<category><![CDATA[Latch]]></category>
		<category><![CDATA[Latch Statistics]]></category>
		<category><![CDATA[Theory]]></category>
		<category><![CDATA[_spin_count]]></category>

		<guid isPermaLink="false">http://andreynikolaev.wordpress.com/?p=2557</guid>
		<description><![CDATA[A week ago I returned from MEDIAS-2011 conference, which was held in Limassol (Cyprus). It was an exciting experience to speak at general Computer Science conference. This was also an opportunity to discuss topics beyond the usual scope of Oracle conferences and see non addicted to Oracle point of view. As you may expect, my [...]<img alt="" border="0" src="http://stats.wordpress.com/b.gif?host=andreynikolaev.wordpress.com&amp;blog=8081483&amp;post=2557&amp;subd=andreynikolaev&amp;ref=&amp;feed=1" width="1" height="1" />]]></description>
		<wfw:commentRss>http://andreynikolaev.wordpress.com/2011/05/22/medias-2011/feed/</wfw:commentRss>
		<slash:comments>1</slash:comments>
	
		<media:content url="http://0.gravatar.com/avatar/67687034a59d04526e0f8d4711b2d380?s=96&#38;d=identicon&#38;r=G" medium="image">
			<media:title type="html">AndreyNikolaev</media:title>
		</media:content>

		<media:content url="http://andreynikolaev.files.wordpress.com/2011/05/medias.jpg?w=111" medium="image">
			<media:title type="html">Medias-2011</media:title>
		</media:content>
	</item>
		<item>
		<title>Divide and conquer the &#8220;true&#8221; mutex contention</title>
		<link>http://andreynikolaev.wordpress.com/2011/05/01/divide-and-conquer-the-true-mutex-contention/</link>
		<comments>http://andreynikolaev.wordpress.com/2011/05/01/divide-and-conquer-the-true-mutex-contention/#comments</comments>
		<pubDate>Sun, 01 May 2011 19:16:55 +0000</pubDate>
		<dc:creator>andreynikolaev</dc:creator>
				<category><![CDATA[11.2]]></category>
		<category><![CDATA[Contention]]></category>
		<category><![CDATA[Mutex]]></category>
		<category><![CDATA[Patches]]></category>

		<guid isPermaLink="false">http://andreynikolaev.wordpress.com/?p=1718</guid>
		<description><![CDATA[Oracle 11.2.0.2 contains enhancements 9282521 and 9239863 named “Library cache: mutex X&#8221; for objects highly contended for. Part I and II. These enhancements introduce new interesting possibilities to tune some types of the mutex contention. Contention for heavily accessed objects can now be divided between multiple copies of object in the library cache. According to [...]<img alt="" border="0" src="http://stats.wordpress.com/b.gif?host=andreynikolaev.wordpress.com&amp;blog=8081483&amp;post=1718&amp;subd=andreynikolaev&amp;ref=&amp;feed=1" width="1" height="1" />]]></description>
		<wfw:commentRss>http://andreynikolaev.wordpress.com/2011/05/01/divide-and-conquer-the-true-mutex-contention/feed/</wfw:commentRss>
		<slash:comments>10</slash:comments>
	
		<media:content url="http://0.gravatar.com/avatar/67687034a59d04526e0f8d4711b2d380?s=96&#38;d=identicon&#38;r=G" medium="image">
			<media:title type="html">AndreyNikolaev</media:title>
		</media:content>
	</item>
		<item>
		<title>&#8220;Cursor: pin S&#8221; mutex contention testcase and diagnostics tools.</title>
		<link>http://andreynikolaev.wordpress.com/2011/04/22/cursor-pin-s-mutex-contention-testcase-and-diagnostics-tools/</link>
		<comments>http://andreynikolaev.wordpress.com/2011/04/22/cursor-pin-s-mutex-contention-testcase-and-diagnostics-tools/#comments</comments>
		<pubDate>Fri, 22 Apr 2011 16:33:22 +0000</pubDate>
		<dc:creator>andreynikolaev</dc:creator>
				<category><![CDATA[11.2]]></category>
		<category><![CDATA[Instrumentation]]></category>
		<category><![CDATA[Mutex]]></category>

		<guid isPermaLink="false">http://andreynikolaev.wordpress.com/?p=1821</guid>
		<description><![CDATA[I like testcases. One testcase results in more understanding than ten page article or weeks of data collection. This is why we need reproducible testcases if we want to explore mutex contention. Testcases will also give me a possibility to demonstrate how to use mutex contention diagnostics tools embedded in Oracle. I will use Oracle [...]<img alt="" border="0" src="http://stats.wordpress.com/b.gif?host=andreynikolaev.wordpress.com&amp;blog=8081483&amp;post=1821&amp;subd=andreynikolaev&amp;ref=&amp;feed=1" width="1" height="1" />]]></description>
		<wfw:commentRss>http://andreynikolaev.wordpress.com/2011/04/22/cursor-pin-s-mutex-contention-testcase-and-diagnostics-tools/feed/</wfw:commentRss>
		<slash:comments>7</slash:comments>
	
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			<media:title type="html">AndreyNikolaev</media:title>
		</media:content>
	</item>
		<item>
		<title>11.2.0.2 is the right patchset for mutexes</title>
		<link>http://andreynikolaev.wordpress.com/2011/03/19/11-2-0-2-is-the-right-patchset-for-mutexes/</link>
		<comments>http://andreynikolaev.wordpress.com/2011/03/19/11-2-0-2-is-the-right-patchset-for-mutexes/#comments</comments>
		<pubDate>Sat, 19 Mar 2011 10:05:19 +0000</pubDate>
		<dc:creator>andreynikolaev</dc:creator>
				<category><![CDATA[11.2]]></category>
		<category><![CDATA[Mutex]]></category>
		<category><![CDATA[Patches]]></category>

		<guid isPermaLink="false">http://andreynikolaev.wordpress.com/?p=1653</guid>
		<description><![CDATA[Many people asked me about the second part of my blog title &#8211; the mutex. This is the first post about it. Mutexes is another Oracle spinlock, which was appeared in version 10.2.0.2. Despite being known since 2005, Oracle mutex internals is still Terra incognita. This post is inspired by several recent escalations due to [...]<img alt="" border="0" src="http://stats.wordpress.com/b.gif?host=andreynikolaev.wordpress.com&amp;blog=8081483&amp;post=1653&amp;subd=andreynikolaev&amp;ref=&amp;feed=1" width="1" height="1" />]]></description>
		<wfw:commentRss>http://andreynikolaev.wordpress.com/2011/03/19/11-2-0-2-is-the-right-patchset-for-mutexes/feed/</wfw:commentRss>
		<slash:comments>13</slash:comments>
	
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			<media:title type="html">AndreyNikolaev</media:title>
		</media:content>
	</item>
		<item>
		<title>Hotsos 2011 Symposium follow-up</title>
		<link>http://andreynikolaev.wordpress.com/2011/03/15/hotsos-2011-symposium-follow-up/</link>
		<comments>http://andreynikolaev.wordpress.com/2011/03/15/hotsos-2011-symposium-follow-up/#comments</comments>
		<pubDate>Tue, 15 Mar 2011 21:58:14 +0000</pubDate>
		<dc:creator>andreynikolaev</dc:creator>
				<category><![CDATA[Uncategorized]]></category>

		<guid isPermaLink="false">http://andreynikolaev.wordpress.com/?p=1643</guid>
		<description><![CDATA[Just returned from the Hotsos 2011 Symposium. It was an exciting experience to be speaker at this legendary conference. Many thanks to the Hotsos team for this opportunity. The Symposium and the presentations were inspiring. I hope my presentation was interesting too. It had to be concise because of one hour time limit. Usually these [...]<img alt="" border="0" src="http://stats.wordpress.com/b.gif?host=andreynikolaev.wordpress.com&amp;blog=8081483&amp;post=1643&amp;subd=andreynikolaev&amp;ref=&amp;feed=1" width="1" height="1" />]]></description>
		<wfw:commentRss>http://andreynikolaev.wordpress.com/2011/03/15/hotsos-2011-symposium-follow-up/feed/</wfw:commentRss>
		<slash:comments>0</slash:comments>
	
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			<media:title type="html">AndreyNikolaev</media:title>
		</media:content>
	</item>
		<item>
		<title>Latch statistics</title>
		<link>http://andreynikolaev.wordpress.com/2011/02/23/latch-statistics/</link>
		<comments>http://andreynikolaev.wordpress.com/2011/02/23/latch-statistics/#comments</comments>
		<pubDate>Wed, 23 Feb 2011 10:36:49 +0000</pubDate>
		<dc:creator>andreynikolaev</dc:creator>
				<category><![CDATA[DTrace]]></category>
		<category><![CDATA[Instrumentation]]></category>
		<category><![CDATA[Latch]]></category>
		<category><![CDATA[Latch Statistics]]></category>
		<category><![CDATA[Theory]]></category>
		<category><![CDATA[Uncategorized]]></category>

		<guid isPermaLink="false">http://andreynikolaev.wordpress.com/?p=1289</guid>
		<description><![CDATA[In previous posts, I investigated how the Oracle process spins and waits for the latch. Now we need the tool to estimate when the latch acquisition works efficiently and when we need to tune it. This tool is the latch statistics. Contemporary Oracle documentation describes v$latch statistics columns as: Statistic: x$ksllt column Documentation description: When [...]<img alt="" border="0" src="http://stats.wordpress.com/b.gif?host=andreynikolaev.wordpress.com&amp;blog=8081483&amp;post=1289&amp;subd=andreynikolaev&amp;ref=&amp;feed=1" width="1" height="1" />]]></description>
		<wfw:commentRss>http://andreynikolaev.wordpress.com/2011/02/23/latch-statistics/feed/</wfw:commentRss>
		<slash:comments>1</slash:comments>
	
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			<media:title type="html">AndreyNikolaev</media:title>
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