diff options
Diffstat (limited to 'sload.buetow.org/content/home.xml')
| -rw-r--r-- | sload.buetow.org/content/home.xml | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/sload.buetow.org/content/home.xml b/sload.buetow.org/content/home.xml new file mode 100644 index 0000000..24c99ae --- /dev/null +++ b/sload.buetow.org/content/home.xml @@ -0,0 +1,54 @@ +<?xml version="1.0" encoding="ISO-8859-1" standalone="yes" ?> +<content> + <pagetitle>SLoad</pagetitle> + <textheader>Calculating server CPU loads</pagetitle> + <text> + <rimg href="?document=images/haskell.png" title="Haskell" /> + <noop>In order to learn functional programming and to calculate server loads at work I programmed in my spare time this small tool using the purely functional programming language </noop> + <namedlink href="http://www.haskell.org">Haskell!</namedlink> + <noop>SLoad is an abbreviation for serverload. SLoad uses basic parameters (current CPU peak, current requests per second) for approximating the need of additional servers.</noop> + </text> + <text>In order to get started check it out from the Subversion repository. You also need to install GHC (the Haskell compiler).</noop> + <code> +pbuetow@earth:~/svn/sload/trunk$ make +ghc SLoad.hs -o sload +</code> + <text>Lets imagine you own an apache server cluster which consists of 12 physical servers. The current maximum CPU usage (CPU peak) is 70%. A single server of the cluster handles at the moment 323 requests per seconds (request peak). And you want to know "does my farm handle 5000000 more requests per day?":</text> + <code> +pbuetow@earth:~/svn/sload/trunk$ ./sload --name=serverfarm.example.net --servers=12 \ + --cpuPeak=70 --peak=323 --requests=5000000 +Requests : 5000000.0 +Percentage of req. to use: 100.0 +Approximated peak: 277.77777 requests per second (Peak = 2 * (5000000.0/(60 * 60 * 10))) +serverfarm.example.net (12.0 Servers): + currentPeakPerServer: 323.0 + currentCpuPeakPerServer: 70.0 + currentPeakPerFarm: 3876.0 + possiblePeakPerFarm: 5038.8 + possibleAddPeak (possiblePeakPerFarm - currentPeakPerFarm): 1162.7998 + addPeakPerServer: 23.148148 + addPeakPerFarm: 277.77777 + leftPeak (possibleAddPeak - addPeakPerFarm): 885.02203 + currentCpuPerPeak (currentCpuPeakPerServer / currentPeakPerServer): 0.21671827 + neededCpuPeakPerServer (currentCpuPeakPerServer + addPeakPerServer * currentCpuPerPeak): \ + 75.016624 +</code> + <text>The approximated peak is being calculated using 2 * (requestsPerDay/10h). This formular has been well-tried and tested. It is not proven that this formular is always right, but it is more a 'worst case' approach. Which is ok for calculating server loads as long as you don't do a 'best case' calculation which may lead to a server overload. The value of neededCpuPeakPerServer shows if the cluster will handle the additional amount of requests. If neededCpuPeakPerSerer is less than 85 it should be ok. A value between 85 and 100 may be critical. A value more than 100 shows that there is definitive not enough power behind your cluster.</text> + <text> + <enumeration> + <enumitem>Requests: Requests per day your server should handle additionally to the current server load. You want to find out if your server cluster will handle this.</enumitem> + <enumitem>Percentage of req. to use: If you use 50, only half of "Requests" will be used in the following calculations.</enumitem>. + <enumitem>currentPeakPerServer: Requests per seconds a single server of the cluster handles (peak)</enumitem> + <enumitem>currentCpuPeakPerServer: The maximum (peak) CPU load of one of your servers.</enumitem> + <enumitem>currentPeakPerFarm: currentPeakPerServer * number of servers in the cluster.</enumitem> + <enumitem>possiblePeakPerFarm: How many requests per seconds your farm may handle (depending on the CPU % which is left)</enumitem> + <enumitem>possibleAddPeak: How many requests per seconds your farm may handle additionally to the CPU usage (depending on the CPU % which is left)</enumitem> + <enumitem>addPeakPerServer: How many requests per seconds a single server of your cluster may handle additionally.</enumitem> + <enumitem>addPeakPerFarm: addPeakPerServer * number of servers in the cluster.</enumitem> + <enumitem>leftPeak: How many requests per second can be handled more even after adding "Requests" to the cluster.</enumitem> + <enumitem>currentCpuPerPeak: How many CPU % is needed for a single request.</enumitem> + <enumitem>neededCpuPeakPerServer: How many CPU % (peak) is needed for a single server of the cluster after adding "Requests".</enumitem> + </enumeration> + </text> +</content> + |