MAXBUF parameter - Revision history

JAL: /* If BTB buffers are used */ add X'02' as possible (V7.7) XMEMOPT default

2017-01-26T01:13:14Z

If BTB buffers are used: add X'02' as possible (V7.7) XMEMOPT default

← Older revision		Revision as of 01:13, 26 January 2017
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	<li>You must set the <var>[[XMEMOPT parameter\|XMEMOPT]]</var> X'02' bit to get more than about 15000-18000 actually allocated to <var>NUMBUF</var>.		<li>You must set the <var>[[XMEMOPT parameter\|XMEMOPT]]</var> X'02' bit to get more than about 15000-18000 actually allocated to <var>NUMBUF</var>.
	<p>		<p>
	~~From version 7.4 onwards, if~~ the M204XSVC module is linked into the nucleus, <var>XMEMOPT</var> defaults to X'03', so the <var>MAXBUF</var> setting should be achieved, provided that sufficient [[Defining the runtime environment (CCAIN)#Calculating region size\|REGION]] is available. </p></li>		If the M204XSVC module is linked into the nucleus, <var>XMEMOPT</var> defaults to X'03' (as of version 7.4) or X'02' (as of version 7.7), so the <var>MAXBUF</var> setting should be achieved, provided that sufficient [[Defining the runtime environment (CCAIN)#Calculating region size\|REGION]] is available. </p></li>

	<li>If <var>MAXBUF</var> is set to a value less than <var>[[MINBUF parameter\|MINBUF]]</var>, <var>MAXBUF</var> is automatically reset to the value of <var>MINBUF</var>, and the following message is issued:		<li>If <var>MAXBUF</var> is set to a value less than <var>[[MINBUF parameter\|MINBUF]]</var>, <var>MAXBUF</var> is automatically reset to the value of <var>MINBUF</var>, and the following message is issued:

JAL: add 7.7 change

2016-08-23T23:50:48Z

add 7.7 change

← Older revision		Revision as of 23:50, 23 August 2016
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	==Description==		==Description==
	<p>		<p>
	~~The~~ maximum number of in-memory file page buffers that can be allocated during <var class="product">Model 204</var> initialization</p>		<var>MAXBUF</var> specifies the maximum number of in-memory file page buffers that can be allocated below the bar (BTB) during <var class="product">Model 204</var> initialization.</p>
	<p>		<p>
	The actual number of pages allocated to the disk buffer pool can be identified by viewing the parameter <var>[[NUMBUF parameter\|NUMBUF]]</var>.</p>		The actual number of BTB pages allocated to the disk buffer pool can be identified by viewing the parameter <var>[[NUMBUF parameter\|NUMBUF]]</var>.</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>
	If <var>[[NLRUQ parameter\|NLRUQ]]</var> is set greater than 1, then the value of <var>MAXBUF</var> is rounded up to a multiple of <var>NLRUQ</var>. The maximum setting is 300000. ~~Also, you~~ must set <var>[[~~XMEMOPT_parameter~~\|XMEMOPT]]</var>=X'02' to get more than about 15000-18000 ~~or so~~ actually allocated to <var>NUMBUF</var>. From V7.4 onwards, if the M204XSVC module has been linked into the nucleus, then <var>XMEMOPT</var> defaults to X'03', which includes the X'02' setting, and thus the <var>MAXBUF</var> setting should always be achieved, provided that sufficient REGION is available. </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>If <var>[[NLRUQ parameter\|NLRUQ]]</var> is set greater than 1, then the value of <var>MAXBUF</var> is rounded up to a multiple of <var>NLRUQ</var>. The maximum setting is 300000. </li>

			<li>You must set the <var>[[XMEMOPT parameter\|XMEMOPT]]</var> X'02' bit to get more than about 15000-18000 actually allocated to <var>NUMBUF</var>.
	<p>		<p>
	If <var>MAXBUF</var> is set to a value less than <var>[[~~MINBUF_parameter~~\|MINBUF]]</var>, <var>MAXBUF</var> is automatically reset to the value of <var>MINBUF</var> and the following message is issued: ~~</p>~~		From version 7.4 onwards, if the M204XSVC module is linked into the nucleus, <var>XMEMOPT</var> defaults to X'03', so the <var>MAXBUF</var> setting should be achieved, provided that sufficient [[Defining the runtime environment (CCAIN)#Calculating region size\|REGION]] is available. </p></li>
	<p class="code">M204.1190: MAXBUF SET TO SAME VALUE AS MINBUF -%C
			<li>If <var>MAXBUF</var> is set to a value less than <var>[[MINBUF parameter\|MINBUF]]</var>, <var>MAXBUF</var> is automatically reset to the value of <var>MINBUF</var>, and the following message is issued:
			<p class="code">M204.1190: MAXBUF SET TO SAME VALUE AS MINBUF -<i>%C</i>
			</p></li>

			<li>You can use the <var>[[MONITOR command: Disk buffers\|MONITOR DISKBUFF]]</var> command to display, from each table of each file, the number of BTB pages that are currently located in the disk buffers.</li>

			<li>If the prefetch feature is enabled (<var>[[SEQOPT parameter\|SEQOPT]]</var>=1), then the <var>MAXBUF</var> parameter must be resized based on the following formula:
			<p class="code">MAXBUF = [[NUSERS parameter\|NUSERS]] * (4 + 2 * (Maximum FOR EACH RECORD loop nest level))
	</p>		</p>
	<p>		<p>
	~~You can use the <var>[[MONITOR_command:_Disk_buffers\|MONITOR DISKBUFF]]</var> command to display, from each table of each file, the number of pages that are currently located in the disk buffers.</p>~~		The prefetch feature is described in [[Record loops#The prefetch (look-ahead read) feature\|The prefetch (look-ahead read) feature]] and in [[Performance monitoring and tuning#Prefetch feature\|Prefetch feature]]. </p></li>
	~~<p>~~		</ul>
	~~If the prefetch feature is enabled (<var>[[SEQOPT_parameter\|SEQOPT]]</var>=1), then the <var>MAXBUF</var> parameter must be resized based on the following formula: </p>~~
	~~<p class="code">MAXBUF = <var>[[NUSERS_parameter\|NUSERS]]</var> * (4 + 2 * (Maximum FOR EACH RECORD loop nest level))~~
	~~</p>~~
	~~<p>~~
	The prefetch feature is described in [[Record loops#The prefetch (look-ahead read) feature\|The prefetch (look-ahead read) feature]] and in [[Performance monitoring and tuning#Prefetch feature\|Prefetch feature]]. </p>

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

JAL: /* Description */ typo

2016-08-08T21:31:41Z

Description: typo

← Older revision		Revision as of 21:31, 8 August 2016
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	</p>		</p>
	<p>		<p>
	The prefetch feature is described in [[Record loops#The prefetch (look-ahead read) feature\|The prefetch (look-ahead read) feature]] and in [[Performance monitoring and tuning#Prefetch feature\|~~Prefetchfeature~~]]. </p>		The prefetch feature is described in [[Record loops#The prefetch (look-ahead read) feature\|The prefetch (look-ahead read) feature]] and in [[Performance monitoring and tuning#Prefetch feature\|Prefetch feature]]. </p>

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

DCameron: /* Description */

2015-07-06T14:16:44Z

Description

← Older revision		Revision as of 14:16, 6 July 2015
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	<p>		<p>
	If the prefetch feature is enabled (<var>[[SEQOPT_parameter\|SEQOPT]]</var>=1), then the <var>MAXBUF</var> parameter must be resized based on the following formula: </p>		If the prefetch feature is enabled (<var>[[SEQOPT_parameter\|SEQOPT]]</var>=1), then the <var>MAXBUF</var> parameter must be resized based on the following formula: </p>
	<p class="code">MAXBUF = NUSERS * (4 + 2 * (Maximum FOR EACH RECORD loop nest level))		<p class="code">MAXBUF = <var>[[NUSERS_parameter\|NUSERS]]</var> * (4 + 2 * (Maximum FOR EACH RECORD loop nest level))
	</p>		</p>
	<p>		<p>

DCameron: /* Description */

2015-07-06T14:13:25Z

Description

← Older revision		Revision as of 14:13, 6 July 2015
Line 28:		Line 28:
	You can use the <var>[[MONITOR_command:_Disk_buffers\|MONITOR DISKBUFF]]</var> command to display, from each table of each file, the number of pages that are currently located in the disk buffers.</p>		You can use the <var>[[MONITOR_command:_Disk_buffers\|MONITOR DISKBUFF]]</var> command to display, from each table of each file, the number of pages that are currently located in the disk buffers.</p>
	<p>		<p>
	If the prefetch feature is enabled (<var>[[SEQOPT_parameter\|SEQOPT=1]]</var>), then the <var>MAXBUF</var> parameter must be resized based on the following formula: </p>		If the prefetch feature is enabled (<var>[[SEQOPT_parameter\|SEQOPT]]</var>=1), then the <var>MAXBUF</var> parameter must be resized based on the following formula: </p>
	<p class="code">MAXBUF = NUSERS * (4 + 2 * (Maximum FOR EACH RECORD loop nest level))		<p class="code">MAXBUF = NUSERS * (4 + 2 * (Maximum FOR EACH RECORD loop nest level))
	</p>		</p>

DCameron: /* Description */

2015-07-06T14:12:52Z

Description

← Older revision		Revision as of 14:12, 6 July 2015
Line 28:		Line 28:
	You can use the <var>[[MONITOR_command:_Disk_buffers\|MONITOR DISKBUFF]]</var> command to display, from each table of each file, the number of pages that are currently located in the disk buffers.</p>		You can use the <var>[[MONITOR_command:_Disk_buffers\|MONITOR DISKBUFF]]</var> command to display, from each table of each file, the number of pages that are currently located in the disk buffers.</p>
	<p>		<p>
	If the prefetch feature is enabled (<var>[[SEQOPT_parameter\|SEQOPT=1]]</~~code~~>), then the <var>MAXBUF</var> parameter must be resized based on the following formula: </p>		If the prefetch feature is enabled (<var>[[SEQOPT_parameter\|SEQOPT=1]]</var>), then the <var>MAXBUF</var> parameter must be resized based on the following formula: </p>
	<p class="code">MAXBUF = NUSERS * (4 + 2 * (Maximum FOR EACH RECORD loop nest level))		<p class="code">MAXBUF = NUSERS * (4 + 2 * (Maximum FOR EACH RECORD loop nest level))
	</p>		</p>

DCameron: /* Description */

2015-07-06T14:12:24Z

Description

← Older revision		Revision as of 14:12, 6 July 2015
Line 26:		Line 26:
	</p>		</p>
	<p>		<p>
	You can use the <var>[[MONITOR_command:_Disk_buffers\|MONITOR DISKBUFF</var> command to display, from each table of each file, the number of pages that are currently located in the disk buffers.</p>		You can use the <var>[[MONITOR_command:_Disk_buffers\|MONITOR DISKBUFF]]</var> command to display, from each table of each file, the number of pages that are currently located in the disk buffers.</p>
	<p>		<p>
	If the prefetch feature is enabled (<var>[[SEQOPT_parameter\|SEQOPT=1]]</code>), then the <var>MAXBUF</var> parameter must be resized based on the following formula: </p>		If the prefetch feature is enabled (<var>[[SEQOPT_parameter\|SEQOPT=1]]</code>), then the <var>MAXBUF</var> parameter must be resized based on the following formula: </p>

DCameron: /* Description */

2015-07-06T14:11:37Z

Description

← Older revision		Revision as of 14:11, 6 July 2015
Line 26:		Line 26:
	</p>		</p>
	<p>		<p>
	You can use the <~~code~~>MONITOR DISKBUFF</~~code~~> command to display, from each table of each file, the number of pages that are currently located in the disk buffers.</p>		You can use the <var>[[MONITOR_command:_Disk_buffers\|MONITOR DISKBUFF</var> command to display, from each table of each file, the number of pages that are currently located in the disk buffers.</p>
	<p>		<p>
	If the prefetch feature is enabled (<~~code~~>SEQOPT=1</code>), then the <var>MAXBUF</var> parameter must be resized based on the following formula: </p>		If the prefetch feature is enabled (<var>[[SEQOPT_parameter\|SEQOPT=1]]</code>), then the <var>MAXBUF</var> parameter must be resized based on the following formula: </p>
	<p class="code">MAXBUF = NUSERS * (4 + 2 * (Maximum FOR EACH RECORD loop nest level))		<p class="code">MAXBUF = NUSERS * (4 + 2 * (Maximum FOR EACH RECORD loop nest level))
	</p>		</p>

DCameron: /* Description */

2015-07-06T14:08:53Z

Description

← Older revision		Revision as of 14:08, 6 July 2015
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	If <var>[[NLRUQ parameter\|NLRUQ]]</var> is set greater than 1, then the value of <var>MAXBUF</var> is rounded up to a multiple of <var>NLRUQ</var>. The maximum setting is 300000. Also, you must set <var>[[XMEMOPT_parameter\|XMEMOPT]]</var>=X'02' to get more than about 15000-18000 or so actually allocated to <var>NUMBUF</var>. From V7.4 onwards, if the M204XSVC module has been linked into the nucleus, then <var>XMEMOPT</var> defaults to X'03', which includes the X'02' setting, and thus the <var>MAXBUF</var> setting should always be achieved, provided that sufficient REGION is available. </p>		If <var>[[NLRUQ parameter\|NLRUQ]]</var> is set greater than 1, then the value of <var>MAXBUF</var> is rounded up to a multiple of <var>NLRUQ</var>. The maximum setting is 300000. Also, you must set <var>[[XMEMOPT_parameter\|XMEMOPT]]</var>=X'02' to get more than about 15000-18000 or so actually allocated to <var>NUMBUF</var>. From V7.4 onwards, if the M204XSVC module has been linked into the nucleus, then <var>XMEMOPT</var> defaults to X'03', which includes the X'02' setting, and thus the <var>MAXBUF</var> setting should always be achieved, provided that sufficient REGION is available. </p>
	<p>		<p>
	If <var>MAXBUF</var> is set to a value less than <var>MINBUF</var>, <var>MAXBUF</var> is automatically reset to the value of <var>MINBUF</var> and the following message is issued: </p>		If <var>MAXBUF</var> is set to a value less than <var>[[MINBUF_parameter\|MINBUF]]</var>, <var>MAXBUF</var> is automatically reset to the value of <var>MINBUF</var> and the following message is issued: </p>
	<p class="code">M204.1190: MAXBUF SET TO SAME VALUE AS MINBUF -%C		<p class="code">M204.1190: MAXBUF SET TO SAME VALUE AS MINBUF -%C
	</p>		</p>

DCameron: /* Description */

2015-07-06T14:01:20Z

Description

← Older revision		Revision as of 14:01, 6 July 2015
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	The actual number of pages allocated to the disk buffer pool can be identified by viewing the parameter <var>[[NUMBUF parameter\|NUMBUF]]</var>.</p>		The actual number of pages allocated to the disk buffer pool can be identified by viewing the parameter <var>[[NUMBUF parameter\|NUMBUF]]</var>.</p>
	<p>		<p>
	If <var>[[NLRUQ parameter\|NLRUQ]]</var> is set greater than 1, then the value of <var>MAXBUF</var> is rounded up to a multiple of <var>NLRUQ</var>. The maximum setting is 300000. Also, you must set XMEMOPT=X'02' to get more than about 15000-18000 or so actually allocated to <var>NUMBUF</var>. From V7.4 onwards, if the M204XSVC module has been linked into the nucleus, then <var>XMEMOPT</var> defaults to X'03', which includes the X'02' setting, and thus the <var>MAXBUF</var> setting should always be achieved, provided that sufficient REGION is available. </p>		If <var>[[NLRUQ parameter\|NLRUQ]]</var> is set greater than 1, then the value of <var>MAXBUF</var> is rounded up to a multiple of <var>NLRUQ</var>. The maximum setting is 300000. Also, you must set <var>[[XMEMOPT_parameter\|XMEMOPT]]</var>=X'02' to get more than about 15000-18000 or so actually allocated to <var>NUMBUF</var>. From V7.4 onwards, if the M204XSVC module has been linked into the nucleus, then <var>XMEMOPT</var> defaults to X'03', which includes the X'02' setting, and thus the <var>MAXBUF</var> setting should always be achieved, provided that sufficient REGION is available. </p>
	<p>		<p>
	If <var>MAXBUF</var> is set to a value less than <var>MINBUF</var>, <var>MAXBUF</var> is automatically reset to the value of <var>MINBUF</var> and the following message is issued: </p>		If <var>MAXBUF</var> is set to a value less than <var>MINBUF</var>, <var>MAXBUF</var> is automatically reset to the value of <var>MINBUF</var> and the following message is issued: </p>