Skip to main content

kvm ksm tuning

Context

I am running a no-brand machine, 

  • CentOS 6.3
  • 2 cores
  • 8GB RAM
  • 1 SATA disk

On this I fired 6 virtual machines

  • 2 Centos 6, 1GB RAM each
  • 4 Windows XP, 2GB RAM each

The reader probably noticed I overbooked RAM: If all the VM will use the available RAM it will fill up to 10GB.

I wanted to test the KSM effect on this. The default KSM settings on this OS is:

 KSM_MONITOR_INTERVAL=60
KSM_SLEEP_MSEC=100
KSM_NPAGES_MAX=1500

The result I got is:

  • Memory usage fits in RAM (very low swap usage
  • Too high CPU usage for scanning "same pages" (constantly using the equivalent of 70% of 1 core)
  • Disk IO is reasonnable, but on the other hand load average is high (10)
  • The Windows XP VM are desperately slow (not a surprise)

Tuning

Before tuning, I collected what ressource I could use more

  • This machine can bear more disk IO: I can use swap and RAM a bit more
  • This weak CPU should be a bit more used by VMs instead of KSM

My fisrt idea is to make KSM check less often. This is my new KSM setting:

KSM_MONITOR_INTERVAL=600
KSM_SLEEP_MSEC=1000
KSM_NPAGES_MAX=5000

The result is:

  • Less load average (now 6)
  • Less CPU used (now about 40% of 1 core)
  • More swap used, but IO statistics are still OK (IO Wait, IO throughput)

I'll still wait for users feedback before sticking to this setting (or not).

Popular posts from this blog

npm run build base-href

Using NPM to specify base-href When building an Angular application, people usually use "ng" and pass arguments to that invocation. Typically, when wanting to hard code "base-href" in "index.html", one will issue: ng build --base-href='https://ngx.rktmb.org/foo' I used to build my angular apps through Bamboo or Jenkins and they have a "npm" plugin. I got the habit to build the application with "npm run build" before deploying it. But the development team once asked me to set the "--base-href='https://ngx.rktmb.org/foo'" parameter. npm run build --base-href='https://ngx.rktmb.org/foo did not set the base href in indext.html After looking for a while, I found https://github.com/angular/angular-cli/issues/13560 where it says: You need to use −− to pass arguments to npm scripts. This did the job! The command to issue is then: npm run build -- --base-href='https://ngx.rktmb.org/foo&

Jenkins invalid privatekey

Publish over SSH, Message "invalid privatekey:" With quite recent (June-July 2020) installations of Jenkins and OpenSSH, I have the following error message when using the "Deploy overs SSH" Jenkins plug-in and publishing artifacts to the target overs SSH: jenkins.plugins.publish_over.BapPublisherException: Failed to add SSH key. Message [invalid privatekey: [B@d8d395a] This problem seems to be referenced here: https://issues.jenkins-ci.org/browse/JENKINS-57495 Just regenerate a key with the right parameters To solve it: ssh-keygen -t rsa -b 4096 Or ssh-keygen -t rsa -b 4096 -m PEM

Emacs TypeScript Development

Emacs Configuration for Typescript In order to comfortably develop on Node, React or Angular projects with Emacs, TIDE is a good solution. We have TypeScript code highlight (that is the minimum!) and code completion based on the codebase (not only on locally defined and builtins) In order to achieve that: Install Emacs (24+) Install Node Install Typescript (which will provide "tsserver") Install TIDE and some usefull dependencies Configure Emacs to use all those Node is then installed in " /home/mihamina/Apps/node-v12.18.0-linux-x64/bin ": you should add it to your PATH. Installing Typescript is done with: npm install --save typescript @types/browserify After that, "tsserver" will be in " /home/mihamina/node_modules/.bin " Then comes the installation of TIDE: With the Emacs package manager, M-x package-install , install "tide". Do the same for "web-mode", "flycheck", "company" "js2-mode" and "