Re: [vserver] make the host safe with 10% of ressources :)

From: ADNET Ghislain <gadnet_at_aqueos.com>
Date: Wed 05 Sep 2007 - 09:14:10 BST
Message-ID: <46DE6552.2040509@aqueos.com>

thanks for the answers :)
> Let's see the settings for the vserver:
>
> My goal is to limit the physical ram to something like 80/90% of the
> ram , same thing for the swap so the host still got:
>
> - 10% of cpu
>
>
>
ok thanks i will remove the idle-time fair share, so i guess you cannot say:

9 guest, 1 host
- 10% of CPU for the host
- 10% of cpu per guest with idle time of 8/10 for the guests t share (so
i allways keep 10% for host)

i have to choose between 10% per guest/host HARD LIMIT or 10%+ idle time
for all host included. Understood thanks :)

 By the way i saw that if you make the mistake of doing:

 sudo vsched --xid 40134 --fill-rate 0 --interval 0

you will freeze the whole computer, not only the guest (this was an
error i wanted to put the fillrate2 and interval2 at zero to have hard
limit). Is it normal , it should only freeze the guest to make this
error i guess ?

>
>> - 10% of ram
>>
>
> very hard to do, unless you switch off overcommitment
> (btw, this isn't terribly important, as ram can always
> be freed by discading buffers and read only mappings
>
yes but the guest is consumming all the memory and then swap like crazy.
I'd like to keep control of the host when the guest goes mad so i can
stop or restart it or constrain it :)

>
>> - 10% of swap
>>
>
> not implemented yet, but having strict limits to the
> guest memory will automagically leave some of the swap
> space (swap+ram - Sum[guests]) unused by guest processes
>
ok, does the RSS limit include swap size as well i was beleiving it was
only a limit on the physical memory ?

the problem i face is that a guest (i have only 1 guest here) is taking
all the memory. The host is therefor unreachable because the guest has
all memory and swap like crazy. My goal is to keep 10% of the memory for
the host so i still can launch a process there. How will you do that if
this is possible ? turn off overcommitment and restrict memory to 90%
of the pages ?

 My try lead to a server where the swap seems disabled (i have nothing
in the swap 0k since days so i wonder it allways had something before i
limit RSS but perhaps this is not the case and the swap state is not a
consequence of limiting my guest RSS.

> but if you really want absolute memory control and a
> guarantee that no process will get more memory than
> available, then you have to turn off overcommitment
> on your linux system
>
>
hum i wonder how bad this will be, i guess that if this is on by default
this is not a good idea to change it. If anyone has experience on this
i will be glad to hear it , how do you control the ram sharing between
guests ?

-- 
Cordialement,
Ghislain

Received on Wed Sep 5 09:14:32 2007
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