From: Gleb Natapov <gleb@redhat.com>
To: Sasha Levin <levinsasha928@gmail.com>
Cc: kvm <kvm@vger.kernel.org>
Subject: Re: APIC lookups
Date: Fri, 2 Sep 2011 21:13:23 +0300 [thread overview]
Message-ID: <20110902181323.GJ26451@redhat.com> (raw)
In-Reply-To: <1314986155.31676.22.camel@lappy>
On Fri, Sep 02, 2011 at 08:55:55PM +0300, Sasha Levin wrote:
> Hi,
>
> I've noticed that kvm_irq_delivery_to_apic() is locating the destination
> APIC by running through kvm_for_each_vcpu() which becomes a scalability
> issue with a large number if vcpus.
>
> I'm thinking about speeding that up using a radix tree for lookups, and
> was wondering if it sounds right.
>
We have to call kvm_apic_match_dest() on each apic to see if it should
get the message. Single message can be sent to more than one apic. It is
likely possible to optimize common case of physical addressing fixed
destination, but then just use array of 256 elements, no need for a tree.
Do you see this function in profiling?
--
Gleb.
next prev parent reply other threads:[~2011-09-02 18:13 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-02 17:55 APIC lookups Sasha Levin
2011-09-02 18:07 ` Sasha Levin
2011-09-02 18:13 ` Gleb Natapov [this message]
2011-09-02 19:08 ` Sasha Levin
2011-09-03 7:32 ` Gleb Natapov
2011-09-03 7:42 ` Sasha Levin
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