From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@redhat.com>
Subject: Re: [patch 0/3] RFC: provide synchronous registers in kvm_run
Date: Thu, 22 Dec 2011 14:35:45 +0200
Message-ID: <4EF32421.8000303@redhat.com>
References: <20111222115646.248800653@de.ibm.com>
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Cc: Marcelo Tossati <mtosatti@redhat.com>,
	Carsten Otte <cotte@de.ibm.com>,
	Alexander Graf <agraf@suse.de>,
	Jens Freimann <jfrei@linux.vnet.ibm.com>,
	Cornelia Huck <cornelia.huck@de.ibm.com>,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	Martin Schwidefsky <schwidefsky@de.ibm.com>,
	KVM <kvm@vger.kernel.org>
To: Christian Borntraeger <borntraeger@de.ibm.com>
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On 12/22/2011 01:56 PM, Christian Borntraeger wrote:
> Avi, Marcelo,
>
> currently userspace can access guest registers via several ioctls. Some
> of these registers might be useful very often. Here the system call overhead
> for ioctl can make an exit more expensive than necessary.
> In a discussion with Alex Graf we concluded that it might be beneficial to
> have a subset of registers available in kvm_run. (The ioctls will also be
> available).
>
> This series provides a prototype implementation together with two example
> users for s390.
>
>

Interesting.  Other archs emulate everything to do with registers in the
kernel, so this is not a fast path.

What workload does this benefit?

-- 
error compiling committee.c: too many arguments to function