From mboxrd@z Thu Jan  1 00:00:00 1970
From: Anthony Liguori <anthony@codemonkey.ws>
Subject: Re: Is guest OS oriented scheduling welcome?
Date: Fri, 24 Apr 2009 08:16:54 -0500
Message-ID: <49F1BBC6.4010906@codemonkey.ws>
References: <820ac2e90904232310g48a978f0wb482deae064aed97@mail.gmail.com>
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To: alex <tomorrowanewday@gmail.com>
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alex wrote:
> just now, I tried cgroup. I admit that as far as only CPU share is
> concerned, cgroup is enough.
>
> However, AFAIK Linux schedules each thread independently, ignoring the
> upper level logic.
>
> for example, suppose VM1 is an SMP one, and it is used to receive
> network packets, which causes it run the TCP/IP stack code frequently.
> The use of spin-lock implies that the lock holder will release it
> fast. However, when vcpu threads are scheduled independently, when one
> vcpu is spinning, the lock holder might be off the CPU! This would
> make the VM's SMP scalability bad.
>   

Sure, but credit doesn't do gang scheduling either.

Instead of gang scheduling, I think the best solution to this problem is 
spin lock paravirtualization.

Regards,

Anthony Liguori