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[Xen-devel] Re: [patch 13/26] Xen-paravirt_ops: Consistently wrap paravirt ops callsites to make them patchable
- To: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
- From: Andi Kleen <ak@xxxxxx>
- Date: 20 Mar 2007 00:42:48 +0100
- Date: Tue, 20 Mar 2007 00:42:48 +0100
- Cc: zach@xxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxx, netdev@xxxxxxxxxxxxxxx, Rusty Russell <rusty@xxxxxxxxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx, David Miller <davem@xxxxxxxxxxxxx>, chrisw@xxxxxxxxxxxx, virtualization@xxxxxxxxxxxxxx, "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>, anthony@xxxxxxxxxxxxx, mingo@xxxxxxx, torvalds@xxxxxxxxxxxxxxxxxxxx, akpm@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Mon, 19 Mar 2007 16:42:00 -0700
- List-id: Xen developer discussion <xen-devel.lists.xensource.com>
> Possibly not, but I'd like to be able to say with confidence that
> running a PARAVIRT kernel on bare hardware has no performance loss
> compared to running a !PARAVIRT kernel. There's the case of small
> instruction sequences which have been replaced with calls (such as
> sti/cli/push;popf/etc),
My guess is that most critical pushf/popf are in spin_lock_irqsave(). It would
be possible to special case that one -- inline it -- and use out of line
versions for all the others.
-Andi
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