touch-packages team mailing list archive

[Jean-Baptiste Lallement <jean-baptiste.lallement@xxxxxxxxxx>]

I think kswapd is a necessary evil and the system can hardly be
prevented of swapping pages in and out. kswapd activity is generally a
symptom of another problem.

I noticed that when kswapd runs for several seconds, it generates lot of
IO and slows down the system drastically. It can be reproduced with dd
and creating large files. The system slow down due IO load is also
observed when apport writes a crash report. Is there a way to tune the
filesystem and improve disk access?

Secondly, when the system swaps heavily it means that some process is
using lot of memory. I looked at the memory consumption and reported bug
1497924 for the memory usage of oxide and apps depending on it
(webbrowser and webapps) Fixing it might improve the situation of memory
consumption and reduce the activity of kswapd.

Finally, setting swappiness to 1 *seems* to improve the situation a
little bit but it's just an impression and I don't have numbers to prove
if it's better one way or the other. Certainly the default of 100 has a
negative impact on performance.

-- 
You received this bug notification because you are a member of Ubuntu
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Ubuntu.
https://bugs.launchpad.net/bugs/1496051

Title:
   kswapd pegging cpu

Status in Canonical System Image:
  Confirmed
Status in lxc-android-config package in Ubuntu:
  Confirmed

Bug description:
  while debugging bug 1491566
  On arale, rc-proposed circa sept 14
  I had launched phone, messaging, browser (on cnn.com), camera (taken pics), gallery (edit mode of pic), clock, ubuntu-system-settings, cut-the-rope, dash (of course) - toggling between them in the spread, just selecting them, mostly clock, browser, gallery
  and at the same time running the phone/text script as found in bug 1491566 (modified to text, call, then text 5 times)

  I just happened to be running top and then noticed process
  kswapd
  would run & peg cpu intermittently, sometimes it would peg the cpu for just 1 second or so, but then sometimes it would appear to run at 95%+ for like 10 seconds or more.
  It didn't seem to follow a particular pattern, but i could definitely tell it was effecting the ui (stalling)

  ogra indicated our swappiness should be very low.
  so i did sudo sysctl vm.swappiness=10 as instructed, however as i continued testing, i continued to see kswapd continue to run and peg the cpu at about the same frequency.

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