From: Eduardo Habkost <ehabkost@redhat.com>
To: Vincent Bernat <vincent@bernat.im>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Richard Henderson <rth@twiddle.net>,
qemu-devel@nongnu.org, Jiri Denemark <jdenemar@redhat.com>,
Kashyap Chamarthy <kchamart@redhat.com>
Subject: Re: [Qemu-devel] [PATCH x86-next v2] target-i386: add PCID flag to Westmere, Sandy Bridge and Ivy Bridge
Date: Tue, 16 Jan 2018 10:41:11 -0200 [thread overview]
Message-ID: <20180116124111.GC627@localhost.localdomain> (raw)
In-Reply-To: <87zi5ite88.fsf@luffy.cx>
On Sat, Jan 13, 2018 at 08:22:31AM +0100, Vincent Bernat wrote:
> ❦ 12 janvier 2018 16:47 -0200, Eduardo Habkost <ehabkost@redhat.com> :
>
> > Adding Westmere-PCID would require adding a Westmere-PCID-IBRS
> > CPU model too, so this is starting to look a bit ridiculous.
> > Sane VM management systems would know how to use
> > "-cpu Westmere,+pcid" without requiring new CPU model entries in
> > QEMU. What's missing in existing management stacks to allow that
> > to happen?
>
> That's what I actually do. So, I am fine with the solution of doing
> nothing. However, it would be nice for unaware people to get the speedup
> of pcid without knowing about it. Maybe we can just forget about
> Westmere and still apply it to Sandy Bridge and Ivy Bridge.
If management stacks today don't let the user choose
"Westmere,+pcid", we probably have no other choice than adding a
Westmere-PCID CPU model. But our management stacks need to be
fixed so we won't need similar hacks in the future.
--
Eduardo
next prev parent reply other threads:[~2018-01-16 12:41 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-09 7:01 [Qemu-devel] [PATCH x86-next v2] target-i386: add PCID flag to Westmere, Sandy Bridge and Ivy Bridge Vincent Bernat
2018-01-12 18:47 ` Eduardo Habkost
2018-01-13 7:22 ` Vincent Bernat
2018-01-16 12:41 ` Eduardo Habkost [this message]
2018-01-16 12:55 ` Vincent Bernat
2018-01-16 15:33 ` Kashyap Chamarthy
2018-01-16 17:08 ` Eduardo Habkost
2018-01-16 17:43 ` Daniel P. Berrange
2018-01-16 22:45 ` Kashyap Chamarthy
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