From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCHv3] kvm/irqchip: Speed up KVM_SET_GSI_ROUTING
Date: Fri, 17 Jan 2014 16:26:56 +0100
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To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>, Gleb Natapov <gleb@minantech.com>, KVM <kvm@vger.kernel.org>, linux-s390 <linux-s390@vger.kernel.org>, Cornelia Huck <cornelia.huck@de.ibm.com>, Jens Freimann <jfrei@linux.vnet.ibm.com>, agraf@suse.de
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Il 17/01/2014 16:03, Christian Borntraeger ha scritto:
> > Well... I love to contradict myself, so: no way this can be accepted
> > this close to the end of the merge window.  :(
> > 
> > synchronize_rcu_expedited() forces a context switch on all CPUs, even
> > those that are not running KVM.  Thus, this patch might help a guest DoS
> > its host by changing the IRQ routing tables in a loop.
> > 
> > So this will have to wait for 3.15.  We have ~2 months to do performance
> > measurements on the v2 patch.  Sorry.
> 
> Any chance that you or Michael can give some performance feedback on v2? All
> my lab systems are s390 and not x86...

Yes, we will help.

Paolo