Messages in this thread |  | | | Date | Fri, 5 Jun 2009 02:51:18 -0700 | | Subject | Re: [RFC] CPU hard limits | | From | Paul Menage <> |
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On Fri, Jun 5, 2009 at 2:48 AM, Dhaval Giani<dhaval@linux.vnet.ibm.com> wrote: >> > Now if 11th group with same shares comes in, then each group will now >> > get 9% of CPU and that 10% guarantee breaks. >> >> So you're trying to guarantee 11 cgroups that they can each get 10% of >> the CPU? That's called over-committing, and while there's nothing >> wrong with doing that if you're confident that they'll not all need >> their 10% at the same time, there's no way to *guarantee* them all >> 10%. You can guarantee them all 9% and hope the extra 1% is spare for >> those that need it (over-committing), or you can guarantee 10 of them >> 10% and give the last one 0 shares. >> >> How would you propose to guarantee 11 cgroups each 10% of the CPU >> using hard limits? >> > > You cannot guarantee 10% to 11 groups on any system (unless I am missing > something). The sum of guarantees cannot exceed 100%.
That's exactly my point. I was trying to counter Bharata's statement, which was:
> > Now if 11th group with same shares comes in, then each group will now > > get 9% of CPU and that 10% guarantee breaks.
which seemed to be implying that this was a drawback of using shares to implement guarantees.
Paul
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