NLRUQ parameter - Revision history

JAL: add link

2016-08-25T23:26:31Z

add link

← Older revision		Revision as of 23:26, 25 August 2016
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	<li>If a <var>[[MONITOR MPLOCK command\|MONITOR MPLOCK]]</var> command output reveals a high conflict count for LRU queue locks, increase <var>NLRUQ</var> and <var>[[NLRUQG parameter\|NLRUQG]]</var>.</li>		<li>If a <var>[[MONITOR MPLOCK command\|MONITOR MPLOCK]]</var> command output reveals a high conflict count for LRU queue locks, increase <var>NLRUQ</var> and <var>[[NLRUQG parameter\|NLRUQG]]</var>.</li>
			</ul>

			==See also==
			<ul>
			<li><var>[[NLRUQG parameter\|NLRUQG]]</var> </li>
	</ul>		</ul>

	[[Category:System parameters]]		[[Category:System parameters]]
	[[Category:Parameters]]		[[Category:Parameters]]

JAL: /* Description */ add 7.7 impact

2016-08-24T00:17:04Z

Description: add 7.7 impact

← Older revision		Revision as of 00:17, 24 August 2016
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	==Description==		==Description==
	<p>		<p>
	The <var>NLRUQ</var> parameter reduces contention on the [[Performance monitoring and tuning#Multiprocessing (MP/204)\|MP]] lock that protects the reuse queues. This MP lock is a primary source of MP overhead. </p>		The <var>NLRUQ</var> parameter reduces contention on the [[Performance monitoring and tuning#Multiprocessing (MP/204)\|MP]] lock that protects the reuse queues. This MP lock is a primary source of MP overhead.
			</p>
	<p>		<p>
	Setting <var>NLRUQ</var> greater than 1 has no benefit in a non-MP run. In fact, in all cases, a setting greater than 1 might result in a slight increase in disk I/O, owing to a loss in precision in the least-recently-used algorithm for managing the disk buffer pool. With <var>NLRUQ</var> greater than 1, it would be possible for a page to be stolen from the buffer pool before one that was less recently used.</p>		Setting <var>NLRUQ</var> greater than 1 has no benefit in a non-MP run. In fact, in all cases, a setting greater than 1 might result in a slight increase in disk I/O, owing to a loss in precision in the least-recently-used algorithm for managing the below the bar (BTB) disk buffer pool. With <var>NLRUQ</var> greater than 1, it would be possible for a page to be stolen from the BTB buffer pool before one that was less recently used.
	<p>		</p>
	<~~code~~>~~NLRUQ=1~~</~~code~~> ~~preserves the single reuse queue model used in releases~~ of ~~<var class="product">~~Model 204</var> ~~before V6R1~~.0. </p>		<blockquote class="note"><b>Note:</b> As of version 7.7 of Model 204, whether BTB buffers are used at all depends entirely on the setting of <var>[[NUMBUFG parameter\|NUMBUFG]]</var>, which activates buffer storage above the bar.
			<ul>
			<li>If <var>NUMBUFG</var> is greater than 0, <i>all</i> buffer pool buffers are forced above the bar — no buffers are below the bar. The <var>MINBUF</var> and <var>NUMBUF</var> parameters are forced to 0, and the other parameters that affect BTB storage (<var>MAXBUF</var>, <var>SPCORE</var>, <var>LDKBMWND</var>, and <var>NLRUQ</var>) are ignored. </li>

			<li>If <var>NUMBUFG</var> is set to 0, all buffers are below the bar, and the settings of the BTB-related parameters are respected and calculated as in pre-7.7 versions. </li>
			</ul>
			</blockquote>

			===If BTB buffers are used===
	<p>		<p>
	<var>NLRUQ</var> is used as a multiplier to determine the minimum number of disk buffers used in an Online: ~~</p>~~		When BTB buffers are being used (that is, <var>NUMBUFG</var> is 0 under version 7.7 or higher, or <var>NUMBUFG</var> is any value under Model 204 prior to 7.7): </p>
			<ul>
			<li><code>NLRUQ=1</code> preserves the single reuse queue model used in releases of <var class="product">Model 204</var> before V6R1.0. </li>

			<li><var>NLRUQ</var> is used as a multiplier to determine the minimum number of BTB disk buffers used in an Online:
	<p class="code"><var>[[MINBUF parameter\|MINBUF]]</var> >= NLRUQ * ((<var>[[NSERVS parameter\|NSERVS]]</var> + <var>[[NSUBTKS parameter\|NSUBTKS]]</var>) * <var>[[MAXOBUF parameter\|MAXOBUF]]</var> + 15)		<p class="code"><var>[[MINBUF parameter\|MINBUF]]</var> >= NLRUQ * ((<var>[[NSERVS parameter\|NSERVS]]</var> + <var>[[NSUBTKS parameter\|NSUBTKS]]</var>) * <var>[[MAXOBUF parameter\|MAXOBUF]]</var> + 15)
	</p>		</p> </li>
	<p>
	A reasonable guess for a proper <var>NLRUQ</var> value adds two for each MP subtask, so a setting of <code>[[NMPSUBS parameter\|NMPSUBS]]=1</code> suggests <code>NLRUQ=3</code>, and <code>NMPSUBS=7</code> suggests <code>NLRUQ=15</code>. </p>		<li>A reasonable guess for a proper <var>NLRUQ</var> value adds two for each MP subtask, so a setting of <code>[[NMPSUBS parameter\|NMPSUBS]]=1</code> suggests <code>NLRUQ=3</code>, and <code>NMPSUBS=7</code> suggests <code>NLRUQ=15</code>. </li>
	<p>
	If <var>NLRUQ</var> is set greater than 1, the values of <var>[[LDKBMWND parameter\|LDKBMWND]]</var>, <var>[[MAXBUF parameter\|MAXBUF]]</var>, and <var>MINBUF</var> are all rounded up to a multiple of <var>NLRUQ</var>. The maximum setting for <var>NLRUQ</var> is 255. </p>		<li>If <var>NLRUQ</var> is set greater than 1, the values of <var>[[LDKBMWND parameter\|LDKBMWND]]</var>, <var>[[MAXBUF parameter\|MAXBUF]]</var>, and <var>MINBUF</var> are all rounded up to a multiple of <var>NLRUQ</var>. The maximum setting for <var>NLRUQ</var> is 255. </li>
	<p>
	If a <var>[[MONITOR MPLOCK command\|MONITOR MPLOCK]]</var> command output reveals a high conflict count for LRU queue locks, increase <var>NLRUQ</var> and <var>[[~~NLRUQG_parameter~~\|NLRUQG]]</var>.</p>		<li>If a <var>[[MONITOR MPLOCK command\|MONITOR MPLOCK]]</var> command output reveals a high conflict count for LRU queue locks, increase <var>NLRUQ</var> and <var>[[NLRUQG parameter\|NLRUQG]]</var>.</li>
			</ul>

	[[Category:System parameters]]		[[Category:System parameters]]
	[[Category:Parameters]]		[[Category:Parameters]]

JAL: minor formatting

2016-08-18T22:49:28Z

minor formatting

← Older revision		Revision as of 22:49, 18 August 2016
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	<dl>		<dl>
	<dt>Default value		<dt>Default value
	<dd>1, also the minimum		<dd>1 (also the minimum)
	<dt>Parameter type		<dt>Parameter type
	<dd>System		<dd>System
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	==Description==		==Description==
	<p>		<p>
	The <var>NLRUQ</var> parameter reduces contention on the [[Performance monitoring and tuning#Multiprocessing (MP/204)\|MP]] lock that protects the reuse queues. </p>		The <var>NLRUQ</var> parameter reduces contention on the [[Performance monitoring and tuning#Multiprocessing (MP/204)\|MP]] lock that protects the reuse queues. This MP lock is a primary source of MP overhead. </p>
	<p>		<p>
	~~This MP lock is a primary source of MP overhead.~~ Setting ~~this parameter to~~ greater than 1 has no benefit in a non-MP run. In fact, in all cases a setting of greater than 1 might result in a slight increase in disk I/O, ~~due~~ to a loss in precision in the least-recently used algorithm for managing the disk buffer pool. With <var>NLRUQ</var> greater than 1, it would be possible for a page to be stolen from the buffer pool before one that was less recently used.</p>		Setting <var>NLRUQ</var> greater than 1 has no benefit in a non-MP run. In fact, in all cases, a setting greater than 1 might result in a slight increase in disk I/O, owing to a loss in precision in the least-recently-used algorithm for managing the disk buffer pool. With <var>NLRUQ</var> greater than 1, it would be possible for a page to be stolen from the buffer pool before one that was less recently used.</p>
	<p>		<p>
	<code>NLRUQ=1</code> preserves the single reuse queue model used in releases of <var class="product">Model 204</var> before V6R1.0. </p>		<code>NLRUQ=1</code> preserves the single reuse queue model used in releases of <var class="product">Model 204</var> before V6R1.0. </p>
	<p>		<p>
	~~In the following formula,~~ <var>NLRUQ</var> is used as a multiplier to determine the minimum number of disk buffers used in an Online: </p>		<var>NLRUQ</var> is used as a multiplier to determine the minimum number of disk buffers used in an Online: </p>
	<p class="code"><var>[[MINBUF parameter\|MINBUF]]</var> >= NLRUQ * ((<var>[[NSERVS parameter\|NSERVS]]</var> + <var>[[NSUBTKS parameter\|NSUBTKS]]</var>) * <var>[[MAXOBUF parameter\|MAXOBUF]]</var> + 15)		<p class="code"><var>[[MINBUF parameter\|MINBUF]]</var> >= NLRUQ * ((<var>[[NSERVS parameter\|NSERVS]]</var> + <var>[[NSUBTKS parameter\|NSUBTKS]]</var>) * <var>[[MAXOBUF parameter\|MAXOBUF]]</var> + 15)
	</p>		</p>
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	If <var>NLRUQ</var> is set greater than 1, the values of <var>[[LDKBMWND parameter\|LDKBMWND]]</var>, <var>[[MAXBUF parameter\|MAXBUF]]</var>, and <var>MINBUF</var> are all rounded up to a multiple of <var>NLRUQ</var>. The maximum setting for <var>NLRUQ</var> is 255. </p>		If <var>NLRUQ</var> is set greater than 1, the values of <var>[[LDKBMWND parameter\|LDKBMWND]]</var>, <var>[[MAXBUF parameter\|MAXBUF]]</var>, and <var>MINBUF</var> are all rounded up to a multiple of <var>NLRUQ</var>. The maximum setting for <var>NLRUQ</var> is 255. </p>
	<p>		<p>
	If ~~you see~~ a ~~high conflict count for LRU queue locks in~~ <var>[[MONITOR MPLOCK command\|MONITOR MPLOCK]]</var> command output, increase <var>NLRUQ</var> and <var>[[NLRUQG_parameter\|NLRUQG]]</var>.</p>		If a <var>[[MONITOR MPLOCK command\|MONITOR MPLOCK]]</var> command output reveals a high conflict count for LRU queue locks, increase <var>NLRUQ</var> and <var>[[NLRUQG_parameter\|NLRUQG]]</var>.</p>

	[[Category:System parameters]]		[[Category:System parameters]]
	[[Category:Parameters]]		[[Category:Parameters]]

JAL: misc formatting

2016-08-18T21:55:07Z

misc formatting

← Older revision		Revision as of 21:55, 18 August 2016
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	==Description==		==Description==
	<p>		<p>
	The <var>NLRUQ</var> parameter reduces contention on the ~~<var>~~[[Performance monitoring and tuning#Multiprocessing (MP/204)\|MP]]~~</var>~~ lock that protects the reuse queues. </p>		The <var>NLRUQ</var> parameter reduces contention on the [[Performance monitoring and tuning#Multiprocessing (MP/204)\|MP]] lock that protects the reuse queues. </p>
	<p>		<p>
	This MP lock is a primary source of MP overhead. Setting this parameter to greater than 1 has no benefit in a non-MP run. In fact, in all cases a setting of greater than 1 might result in a slight increase in disk I/O, due to a loss in precision in the least-recently used algorithm for managing the disk buffer pool. With NLRUQ greater than 1, it would be possible for a page to be stolen from the buffer pool before one that was less recently used.</p>		This MP lock is a primary source of MP overhead. Setting this parameter to greater than 1 has no benefit in a non-MP run. In fact, in all cases a setting of greater than 1 might result in a slight increase in disk I/O, due to a loss in precision in the least-recently used algorithm for managing the disk buffer pool. With <var>NLRUQ</var> greater than 1, it would be possible for a page to be stolen from the buffer pool before one that was less recently used.</p>
	<p>		<p>
	NLRUQ=1 preserves the single reuse queue model used in releases of <var class="product">Model 204</var> before V6R1.0. </p>		<code>NLRUQ=1</code> preserves the single reuse queue model used in releases of <var class="product">Model 204</var> before V6R1.0. </p>
	<p>In the following formula NLRUQ is used as a multiplier to determine the minimum number of disk buffers used in an Online. </p>		<p>
			In the following formula, <var>NLRUQ</var> is used as a multiplier to determine the minimum number of disk buffers used in an Online: </p>
	<p class="code"><var>[[MINBUF parameter\|MINBUF]]</var> >= NLRUQ * ((<var>[[NSERVS parameter\|NSERVS]]</var> + <var>[[NSUBTKS parameter\|NSUBTKS]]</var>) * <var>[[MAXOBUF parameter\|MAXOBUF]]</var> + 15)		<p class="code"><var>[[MINBUF parameter\|MINBUF]]</var> >= NLRUQ * ((<var>[[NSERVS parameter\|NSERVS]]</var> + <var>[[NSUBTKS parameter\|NSUBTKS]]</var>) * <var>[[MAXOBUF parameter\|MAXOBUF]]</var> + 15)
	</p>		</p>
	<p>		<p>
	A reasonable guess for a proper NLRUQ ~~would be adding~~ two for each MP subtask so ~~that~~ a setting of <code>[[NMPSUBS parameter\|NMPSUBS]]=1</code> ~~would suggest~~ <code>NLRUQ=3</code>, and <code>NMPSUBS=7</code> ~~would suggest~~ <code>NLRUQ=15</code>. </p>		A reasonable guess for a proper <var>NLRUQ</var> value adds two for each MP subtask, so a setting of <code>[[NMPSUBS parameter\|NMPSUBS]]=1</code> suggests <code>NLRUQ=3</code>, and <code>NMPSUBS=7</code> suggests <code>NLRUQ=15</code>. </p>
	<p>		<p>
	If NLRUQ is set greater than 1, the values of <var>[[LDKBMWND parameter\|LDKBMWND]]</var>, <var>[[MAXBUF parameter\|MAXBUF]]</var>, and MINBUF are all rounded up to a multiple of NLRUQ. The maximum setting for NLRUQ is 255. </p>		If <var>NLRUQ</var> is set greater than 1, the values of <var>[[LDKBMWND parameter\|LDKBMWND]]</var>, <var>[[MAXBUF parameter\|MAXBUF]]</var>, and <var>MINBUF</var> are all rounded up to a multiple of <var>NLRUQ</var>. The maximum setting for <var>NLRUQ</var> is 255. </p>
	<p>		<p>
	A high conflict count for LRU queue locks ~~that would appear~~ in <var>[[MONITOR MPLOCK command\|MONITOR MPLOCK]]</var> command output ~~indicates that you should~~ increase NLRUQ and <var>[[NLRUQG_parameter\|NLRUQG]]</var>.</p>		If you see a high conflict count for LRU queue locks in <var>[[MONITOR MPLOCK command\|MONITOR MPLOCK]]</var> command output, increase <var>NLRUQ</var> and <var>[[NLRUQG_parameter\|NLRUQG]]</var>.</p>

	[[Category:System parameters]]		[[Category:System parameters]]
	[[Category:Parameters]]		[[Category:Parameters]]

JAL: link repair

2015-09-01T16:35:43Z

link repair

← Older revision		Revision as of 16:35, 1 September 2015
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	==Description==		==Description==
	<p>The NLRUQ parameter reduces contention on the <var>[[~~Performance_monitoring_and_tuning~~#~~Multiprocessing_.28MP.2F204.29~~\|MP]]</var> lock that protects the reuse queues. </p>		<p>
	<p>This MP lock is a primary source of MP overhead. Setting this parameter to greater than 1 has no benefit in a non-MP run. In fact, in all cases a setting of greater than 1 might result in a slight increase in disk I/O, due to a loss in precision in the least-recently used algorithm for managing the disk buffer pool. With NLRUQ greater than 1, it would be possible for a page to be stolen from the buffer pool before one that was less recently used.</p>		The <var>NLRUQ</var> parameter reduces contention on the <var>[[Performance monitoring and tuning#Multiprocessing (MP/204)\|MP]]</var> lock that protects the reuse queues. </p>
	<p>NLRUQ=1 preserves the single reuse queue model used in releases of <var class="product">Model 204</var> before V6R1.0. </p>		<p>
			This MP lock is a primary source of MP overhead. Setting this parameter to greater than 1 has no benefit in a non-MP run. In fact, in all cases a setting of greater than 1 might result in a slight increase in disk I/O, due to a loss in precision in the least-recently used algorithm for managing the disk buffer pool. With NLRUQ greater than 1, it would be possible for a page to be stolen from the buffer pool before one that was less recently used.</p>
			<p>
			NLRUQ=1 preserves the single reuse queue model used in releases of <var class="product">Model 204</var> before V6R1.0. </p>
	<p>In the following formula NLRUQ is used as a multiplier to determine the minimum number of disk buffers used in an Online. </p>		<p>In the following formula NLRUQ is used as a multiplier to determine the minimum number of disk buffers used in an Online. </p>
	<p class="code"><var>[[~~MINBUF_parameter~~\|~~MINUF~~]]</var> >= NLRUQ * ((<var>[[~~NSERVS_parameter~~\|NSERVS]]</var> + <var>[[~~NSUBTKS_parameter~~\|NSUBTKS]]</var>) * <var>[[~~MAXOBUF_parameter~~\|MAXOBUF]]</var> + 15)		<p class="code"><var>[[MINBUF parameter\|MINBUF]]</var> >= NLRUQ * ((<var>[[NSERVS parameter\|NSERVS]]</var> + <var>[[NSUBTKS parameter\|NSUBTKS]]</var>) * <var>[[MAXOBUF parameter\|MAXOBUF]]</var> + 15)
	</p>		</p>
	<p>A reasonable guess for a proper NLRUQ would be adding two for each MP subtask so that a setting of <~~var~~>[[~~NMPSUBS_parameter~~\|NMPSUBS]]</~~var~~>=1 would suggest NLRUQ=3 and NMPSUBS=7 would suggest NLRUQ=15. </p>		<p>
	<p>If NLRUQ is set greater than 1, ~~then~~ the values of <var>[[~~LDKBMWND_parameter~~\|LDKBMWND]]</var>, <var>[[~~MAXBUF_parameter~~\|MAXBUF]]</var>, and MINBUF are all rounded up to a multiple of NLRUQ. The maximum setting for NLRUQ is 255. </p>		A reasonable guess for a proper NLRUQ would be adding two for each MP subtask so that a setting of <code>[[NMPSUBS parameter\|NMPSUBS]]=1</code> would suggest <code>NLRUQ=3</code>, and <code>NMPSUBS=7</code> would suggest <code>NLRUQ=15</code>. </p>
	<p>A high conflict count for LRU queue locks that would appear in <var>[[~~MONITOR_MPLOCK_parameter~~\|MONITOR MPLOCK]]</var> command output indicates that you should increase NLRUQ and <var>[[NLRUQG_parameter\|NLRUQG]]</var>.</p>		<p>
			If NLRUQ is set greater than 1, the values of <var>[[LDKBMWND parameter\|LDKBMWND]]</var>, <var>[[MAXBUF parameter\|MAXBUF]]</var>, and MINBUF are all rounded up to a multiple of NLRUQ. The maximum setting for NLRUQ is 255. </p>
			<p>
			A high conflict count for LRU queue locks that would appear in <var>[[MONITOR MPLOCK command\|MONITOR MPLOCK]]</var> command output indicates that you should increase NLRUQ and <var>[[NLRUQG_parameter\|NLRUQG]]</var>.</p>

	[[Category:System parameters]]		[[Category:System parameters]]
	[[Category:Parameters]]		[[Category:Parameters]]

DCameron: /* Description */

2015-08-25T15:22:23Z

Description

← Older revision		Revision as of 15:22, 25 August 2015
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	<p>A reasonable guess for a proper NLRUQ would be adding two for each MP subtask so that a setting of <var>[[NMPSUBS_parameter\|NMPSUBS]]</var>=1 would suggest NLRUQ=3 and NMPSUBS=7 would suggest NLRUQ=15. </p>		<p>A reasonable guess for a proper NLRUQ would be adding two for each MP subtask so that a setting of <var>[[NMPSUBS_parameter\|NMPSUBS]]</var>=1 would suggest NLRUQ=3 and NMPSUBS=7 would suggest NLRUQ=15. </p>
	<p>If NLRUQ is set greater than 1, then the values of <var>[[LDKBMWND_parameter\|LDKBMWND]]</var>, <var>[[MAXBUF_parameter\|MAXBUF]]</var>, and MINBUF are all rounded up to a multiple of NLRUQ. The maximum setting for NLRUQ is 255. </p>		<p>If NLRUQ is set greater than 1, then the values of <var>[[LDKBMWND_parameter\|LDKBMWND]]</var>, <var>[[MAXBUF_parameter\|MAXBUF]]</var>, and MINBUF are all rounded up to a multiple of NLRUQ. The maximum setting for NLRUQ is 255. </p>
	<p>A high conflict count for LRU queue locks that would appear in MONITOR MPLOCK command output indicates that you should increase NLRUQ and <var>[[NLRUQG_parameter\|NLRUQG]]</var>.</p>		<p>A high conflict count for LRU queue locks that would appear in <var>[[MONITOR_MPLOCK_parameter\|MONITOR MPLOCK]]</var> command output indicates that you should increase NLRUQ and <var>[[NLRUQG_parameter\|NLRUQG]]</var>.</p>
	[[Category:System parameters]]		[[Category:System parameters]]
	[[Category:Parameters]]		[[Category:Parameters]]

DCameron: /* Description */

2015-08-25T15:20:52Z

Description

← Older revision		Revision as of 15:20, 25 August 2015
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	<p class="code"><var>[[MINBUF_parameter\|MINUF]]</var> >= NLRUQ * ((<var>[[NSERVS_parameter\|NSERVS]]</var> + <var>[[NSUBTKS_parameter\|NSUBTKS]]</var>) * <var>[[MAXOBUF_parameter\|MAXOBUF]]</var> + 15)		<p class="code"><var>[[MINBUF_parameter\|MINUF]]</var> >= NLRUQ * ((<var>[[NSERVS_parameter\|NSERVS]]</var> + <var>[[NSUBTKS_parameter\|NSUBTKS]]</var>) * <var>[[MAXOBUF_parameter\|MAXOBUF]]</var> + 15)
	</p>		</p>
	<p>A reasonable guess for a proper NLRUQ would be adding two for each MP subtask so that a NMPSUBS=1 would suggest NLRUQ=3 and NMPSUBS=7 would suggest NLRUQ=15. </p>		<p>A reasonable guess for a proper NLRUQ would be adding two for each MP subtask so that a setting of <var>[[NMPSUBS_parameter\|NMPSUBS]]</var>=1 would suggest NLRUQ=3 and NMPSUBS=7 would suggest NLRUQ=15. </p>
	<p>If NLRUQ is set greater than 1, then the values of LDKBMWND, MAXBUF, and MINBUF are all rounded up to a multiple of NLRUQ. The maximum setting for NLRUQ is 255. </p>		<p>If NLRUQ is set greater than 1, then the values of <var>[[LDKBMWND_parameter\|LDKBMWND]]</var>, <var>[[MAXBUF_parameter\|MAXBUF]]</var>, and MINBUF are all rounded up to a multiple of NLRUQ. The maximum setting for NLRUQ is 255. </p>
	<p>A high conflict count for LRU queue locks that would appear in MONITOR MPLOCK command output indicates that you should increase NLRUQ and NLRUQG.</p>		<p>A high conflict count for LRU queue locks that would appear in MONITOR MPLOCK command output indicates that you should increase NLRUQ and <var>[[NLRUQG_parameter\|NLRUQG]]</var>.</p>
	[[Category:System parameters]]		[[Category:System parameters]]
	[[Category:Parameters]]		[[Category:Parameters]]

DCameron: /* Description */

2015-08-25T15:13:33Z

Description

← Older revision		Revision as of 15:13, 25 August 2015
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	<p>NLRUQ=1 preserves the single reuse queue model used in releases of <var class="product">Model 204</var> before V6R1.0. </p>		<p>NLRUQ=1 preserves the single reuse queue model used in releases of <var class="product">Model 204</var> before V6R1.0. </p>
	<p>In the following formula NLRUQ is used as a multiplier to determine the minimum number of disk buffers used in an Online. </p>		<p>In the following formula NLRUQ is used as a multiplier to determine the minimum number of disk buffers used in an Online. </p>
	<p class="code">MINUF >= NLRUQ * ((NSERVS + NSUBTKS) * MAXOBUF + 15)		<p class="code"><var>[[MINBUF_parameter\|MINUF]]</var> >= NLRUQ * ((<var>[[NSERVS_parameter\|NSERVS]]</var> + <var>[[NSUBTKS_parameter\|NSUBTKS]]</var>) * <var>[[MAXOBUF_parameter\|MAXOBUF]]</var> + 15)
	</p>		</p>
	<p>A reasonable guess for a proper NLRUQ would be adding two for each MP subtask so that a NMPSUBS=1 would suggest NLRUQ=3 and NMPSUBS=7 would suggest NLRUQ=15. </p>		<p>A reasonable guess for a proper NLRUQ would be adding two for each MP subtask so that a NMPSUBS=1 would suggest NLRUQ=3 and NMPSUBS=7 would suggest NLRUQ=15. </p>

DCameron: /* Description */

2015-08-25T15:10:47Z

Description

← Older revision		Revision as of 15:10, 25 August 2015
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	==Description==		==Description==
	<p>The NLRUQ parameter reduces contention on the MP lock that protects the reuse queues. </p>		<p>The NLRUQ parameter reduces contention on the <var>[[Performance_monitoring_and_tuning#Multiprocessing_.28MP.2F204.29\|MP]]</var> lock that protects the reuse queues. </p>
	<p>This MP lock is a primary source of MP overhead. Setting this parameter to greater than 1 has no benefit in a non-MP run. In fact, in all cases a setting of greater than 1 might result in a slight increase in disk I/O, due to a loss in precision in the least-recently used algorithm for managing the disk buffer pool. With NLRUQ greater than 1, it would be possible for a page to be stolen from the buffer pool before one that was less recently used.</p>		<p>This MP lock is a primary source of MP overhead. Setting this parameter to greater than 1 has no benefit in a non-MP run. In fact, in all cases a setting of greater than 1 might result in a slight increase in disk I/O, due to a loss in precision in the least-recently used algorithm for managing the disk buffer pool. With NLRUQ greater than 1, it would be possible for a page to be stolen from the buffer pool before one that was less recently used.</p>
	<p>NLRUQ=1 preserves the single reuse queue model used in releases of <var class="product">Model 204</var> before V6R1.0. </p>		<p>NLRUQ=1 preserves the single reuse queue model used in releases of <var class="product">Model 204</var> before V6R1.0. </p>

DCameron: /* Summary */

2015-08-25T15:08:48Z

Summary

← Older revision		Revision as of 15:08, 25 August 2015
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	<dd>All		<dd>All
	<dt>Introduced		<dt>Introduced
	<dd><var class="product">Model 204 V6.1</var> ~~or earlier~~		<dd><var class="product">Model 204 V6.1</var>
	</dl>		</dl>

	==Description==		==Description==
	<p>The NLRUQ parameter reduces contention on the MP lock that protects the reuse queues. </p>		<p>The NLRUQ parameter reduces contention on the MP lock that protects the reuse queues. </p>