Pagedaemon and shared memory [was: Heavy system load by pagedaemon].

[Yaron Zabary]

On Sun, 28 May 2006 soralx at cydem.org wrote:

> 
> > with 512Mb. The vmware guest (a Windows 2000) is allocated 256Mb. Every
> > once in a while (around five times a day), the machine freezes. The clock
> > on the toolbar stops counting the seconds. I have top running on a session
> > from another machine(it is a second machine I can switch to using KVM)
> > which also freezes (no screen refresh). Disk activity is heavy (lamp is
> > on). After over 30 seconds, the machine is back to normal and everything
> > works fine. The vmware process resident size goesdown from ~200Mb to
> > ~100Mb. I also notices some relations to running acroread 7 with large PDF
> > files (which might also need shared memory for its operation). I had the
> > exact same problem on the same box when I was running FreeBSD 4.10 (which
> > I attributed at first to a bad disk, which was replaced when I upgraded
> > from 4.10 to 6.1).
> 
> Isn't this normal? I noticed long time ago that paging always causes
> freezes, as though there is no context switching during swapping at all.

   I have no problem with the paging. It just seems that the high and low
watermarks are set in such a way that causes the system to freeze for a
very long period. In my second letter I mentioned the fact that it took
around four minutes for the system to become responsive again. My guess is
that tuning the high watermark lower AND having the spread between the
high and low watermarks smaller will make things better. Also, it seems
that there is some issue which is related to shared memory which makes the
problem worse.

> 
> [SorAlx]ridin' VN1500-B2
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-- Yaron.