Re: No space in available paging segments
Re: No space in available paging segments
- Subject: Re: No space in available paging segments
- From: Philip Parker <email@hidden>
- Date: Tue, 20 Aug 2002 23:09:58 -0700
On Tuesday, August 20, 2002, at 10:33 AM, Olivier Cinquin wrote:
On Tuesday, August 20, 2002, at 04:34 , David A. Gatwood wrote:
On Tue, 20 Aug 2002, Olivier Cinquin wrote:
Hello, I was just wondering what the following message means? Could only
find an obscure reference to KDE on the Web...
Aug 20 11:14:55 localhost mach_kernel: (default pager): [KERNEL]: no
space in available paging segments; swapon suggested
I get the message after playing animated gifs I created, which causes an
incredible amount of memory thrashing when played from Web browsers, for
some reason...
Wow. I haven't seen that message since MkLinux DR3. Does your system
crash when this happens?
No, it just gets very unresponsive and spends its time swapping...
The message was repeated more than 100 times within a few minutes.
Olivier
I have not seen this message with MacOS X, however when MacOS X is adding
swap
spaces in /var/vm, it runs like a slug. I experienced this feature early
in
MacOS X, so I modified /etc/rc and changed the arguments to dynamic_pager
to
dynamic_pager -H 40000000 -L 576870920 -S 536870912 -F ${swapdir}/swapfile
So now it creates 524MB swap spaces instead on 80MB, and its performance
was much
more predictable.
Now as to your message, in other VM UNIX's I've run across, they have been
limited to a number of swap devices (16 comes to mind), so perhaps the
system
is looking for more swap space to map, but dynamic_pager cannot add any
more.
16 X 80 = 1280, only ~ 1GB
If you can repeat this situation with the default setup, do a ls -al /var/
vm and
see how many swapfiles there are. Also note that when it does not require
extra
swap spaces, the dynamic_pager will deallocate swapfiles except for the
primary one,
and this also seems to take time, as active pages seem to be consolidated
from one
swapfile to another ... a lot of IO occurs. I wonder if KMAP space is also
consolidated, I'd expect serious pregnant pauses in a non Monolithic Kernel.
Hope this helps
Philip
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