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diff --git a/lib/sasl/doc/src/overload.xml b/lib/sasl/doc/src/overload.xml deleted file mode 100644 index 2f19cd9088..0000000000 --- a/lib/sasl/doc/src/overload.xml +++ /dev/null @@ -1,152 +0,0 @@ -<?xml version="1.0" encoding="utf-8" ?> -<!DOCTYPE erlref SYSTEM "erlref.dtd"> - -<erlref> - <header> - <copyright> - <year>1996</year><year>2013</year> - <holder>Ericsson AB. All Rights Reserved.</holder> - </copyright> - <legalnotice> - Licensed under the Apache License, Version 2.0 (the "License"); - you may not use this file except in compliance with the License. - You may obtain a copy of the License at - - http://www.apache.org/licenses/LICENSE-2.0 - - Unless required by applicable law or agreed to in writing, software - distributed under the License is distributed on an "AS IS" BASIS, - WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. - See the License for the specific language governing permissions and - limitations under the License. - - </legalnotice> - - <title>overload</title> - <prepared>Peter Högfeldt</prepared> - <responsible>Peter Högfeldt</responsible> - <docno></docno> - <approved>(Joe Armstrong)</approved> - <checked></checked> - <date>1996-10-29</date> - <rev>A</rev> - <file>overload.sgml</file> - </header> - <module>overload</module> - <modulesummary>An Overload Regulation Process</modulesummary> - <description> - <warning> - <p> - All functions in this module are deprecated and will be - removed in a future release. - </p> - </warning> - <p><c>overload</c> is a process that indirectly regulates the CPU - usage in the system. The idea is that a main application calls - function - <seealso marker="#request/0"><c>request/0</c></seealso> - before starting a major job and - proceeds with the job if the return value is positive; otherwise - the job must not be started.</p> - <p><c>overload</c> is part of the <c>SASL</c> application and all - configuration parameters are defined there.</p> - <p>A set of two intensities are maintained, the <c>total intensity</c> - and the <c>accept intensity</c>. For that purpose, - there are two configuration parameters, <c>MaxIntensity</c> - and <c>Weight</c>; both are measured in 1/second.</p> - <p>Then total and accept intensities are calculated as - follows. Assume that the time of the current call to - <c>request/0</c> is <c>T(n)</c> and that the time of the - previous call was <c>T(n-1)</c>.</p> - <list type="bulleted"> - <item> - <p>The current <c>total intensity</c>, denoted - <c>TI(n)</c>, is calculated according to the formula</p> - <p><c>TI(n) = exp(-Weight*(T(n) - T(n-1)) * TI(n-1) + Weight</c>,</p> - <p>where <c>TI(n-1)</c> is the previous <c>total intensity</c>.</p> - </item> - <item> - <p>The current <c>accept intensity</c>, denoted - <c>AI(n)</c>, is determined by the formula</p> - <p><c>AI(n) = exp(-Weight*(T(n) - T(n-1)) * AI(n-1) + Weight</c>,</p> - <p>where <c>AI(n-1)</c> is the previous <c>accept intensity</c>, - if the value of <c>exp(-Weight*(T(n) - T(n-1)) * AI(n-1)</c> - is less than <c>MaxIntensity</c>. Otherwise the value is</p> - <p><c>AI(n) = exp(-Weight*(T(n) - T(n-1)) * AI(n-1)</c></p> - </item> - </list> - <p>The value of configuration parameter <c>Weight</c> controls the - speed with which the calculations of intensities react to - changes in the underlying input intensity. The inverted value of - <c>Weight</c>, <c>T = 1/Weight</c>, can be thought of as the - "time constant" of the intensity calculation formulas. For example, - if <c>Weight = 0.1</c>, a change in the underlying input intensity is - reflected in <c>total intensity</c> and <c>accept intensity</c> within - about 10 seconds.</p> - <p>The overload process defines one alarm, which it sets using - <c>alarm_handler:set_alarm(Alarm)</c>. <c>Alarm</c> is defined - as follows:</p> - <taglist> - <tag><c>{overload, []}</c></tag> - <item> - <p>This alarm is set when the current <c>accept intensity</c> exceeds - <c>MaxIntensity</c>.</p> - </item> - </taglist> - <p>A new request is not accepted until the current <c>accept - intensity</c> has fallen below <c>MaxIntensity</c>. To prevent the - overload process from generating many set/reset alarms, the - alarm is not reset until the current <c>accept intensity</c> has fallen - below 75% of <c>MaxIntensity</c>; it is not until then that - the alarm can be set again.</p> - </description> - - <funcs> - <func> - <name>request() -> accept | reject</name> - <fsummary>Requests to proceed with current job.</fsummary> - <desc> - <p>Returns <c>accept</c> or <c>reject</c> depending on the - current value of the <c>accept intensity</c>.</p> - <p>The application - calling this function is to proceed with the job in - question if the return value is <c>accept</c>; otherwise it - is not to continue with that job.</p> - </desc> - </func> - - <func> - <name>get_overload_info() -> OverloadInfo</name> - <fsummary>Returns current overload information data.</fsummary> - <type> - <v>OverloadInfo = [{total_intensity, TotalIntensity}, - {accept_intensity, AcceptIntensity}, {max_intensity, - MaxIntensity}, {weight, Weight}, {total_requests, - TotalRequests}, {accepted_requests, AcceptedRequests}].</v> - <v>TotalIntensity = float() > 0</v> - <v>AcceptIntensity = float() > 0</v> - <v>MaxIntensity = float() > 0</v> - <v>Weight = float() > 0</v> - <v>TotalRequests = integer()</v> - <v>AcceptedRequests = integer()</v> - </type> - <desc> - <p>Returns:</p> - <list type="bulleted"> - <item>Current total and accept intensities</item> - <item>Configuration parameters</item> - <item>Absolute counts of the total number of requests</item> - <item>Accepted number of requests (since the overload - process was started)</item> - </list> - </desc> - </func> - </funcs> - - <section> - <title>See Also</title> - <p><seealso marker="alarm_handler"><c>alarm_handler(3)</c></seealso>, - <seealso marker="sasl_app"><c>sasl(6)</c></seealso></p> - </section> -</erlref> - |