linux-kernel - Re: [kvm-devel] [PATCH 0/2][KVM] guest time accounting

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <200708131615.42643.borntraeger@de.ibm.com>
Date:	Mon, 13 Aug 2007 16:15:42 +0200
From:	Christian Borntraeger <borntraeger@...ibm.com>
To:	kvm-devel@...ts.sourceforge.net
Cc:	Laurent Vivier <Laurent.Vivier@...l.net>,
	Avi Kivity <avi@...ranet.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	virtualization <virtualization@...ts.linux-foundation.org>,
	cotte@...ibm.com
Subject: Re: [kvm-devel] [PATCH 0/2][KVM] guest time accounting

Am Montag, 13. August 2007 schrieb Laurent Vivier:
> > [copying Ingo and Rusty]

@Avi, seems that sourceforge is mangling the cc list?

> > 
> > The patches look good.  A couple of comments:
> > 
> > - perhaps the new fields should be guarded by a #ifdef CONFIG_HYPERVISOR
> > (selected by CONFIG_KVM)?  that way the (minor) additional overhead is
> > only incurred if it can possibly be used.  I imagine that our canine
> > cousin will want to use this as well.
> 
> There is also a CONFIG_VIRTUALIZATION and a CONFIG_VIRT_CPU_ACCOUNTING (from
> s390 and powerpc) Which one to use ?

CONFIG_VIRT_CPU_ACCOUNTING is used for the precise accouting of user,system, 
steal and irq time on these platforms and is not what you want for the on/off 
decision. 
> 
> I'm wondering if we can have a more accurate accounting:
> 
> - For the moment we add all system time since the previous entering to the
> VCPU to the guest time (and I guess there is some real system time in
> it ???) 
> - Perhaps we can sum nanoseconds spent in the VCPU and add it to cpustat
> when these ns are greater than 1 ms ? (I'm trying to make something in this 
way)

If you look at the patch I have posted some minutes ago, I use a method 
similar to irq_enter and irq_exit to separate real system time from guest 
time. 

> > - I think that there is per-task accounting of user time and system
> > time; that should be extended as well.
> it should be easy to do too...

We have to make sure that userspace doesnt break, but yes we should have a 
guest time for processes as well. 

Christian
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/