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[Xen-devel] Re: [PATCH RFC V2 3/5] jump_label: if a key has already been initialized, don't nop it out
- To: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
- From: Steven Rostedt <rostedt@xxxxxxxxxxx>
- Date: Thu, 06 Oct 2011 18:08:34 -0400
- Cc: Linux, Jan, the arch/x86 maintainers <x86@xxxxxxxxxx>, Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>, David Daney <david.daney@xxxxxxxxxx>, peterz@xxxxxxxxxxxxx, Jason Baron <jbaron@xxxxxxxxxx>, Glauber <jang@xxxxxxxxxxxxxxxxxx>, Mailing List <linux-kernel@xxxxxxxxxxxxxxx>, rth@xxxxxxxxxx, Michael Ellerman <michael@xxxxxxxxxxxxxx>, Xen Devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, "David S. Miller" <davem@xxxxxxxxxxxxx>
- Delivery-date: Thu, 06 Oct 2011 15:09:35 -0700
- List-id: Xen developer discussion <xen-devel.lists.xensource.com>
On Thu, 2011-10-06 at 14:39 -0700, Jeremy Fitzhardinge wrote:
> I'm not sure it would be a win, necessarily. My test with back-to-back
> jmp2 was definitely slower than with the nop padding it out to 5 bytes;
> I suspect that's a result of having too many jmps within one cacheline.
> Of course, there's no reason why the CPU would optimise for jumps to
> jumps, so perhaps its just hitting a "stupid programmer" path.
Just a note. Micro-benchmarks are known to be as good as political polls
and statistics. They show a much different view of the world than what
is really there.
-- Steve
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- References:
- [Xen-devel] [PATCH RFC V2 0/5] jump-label: allow early jump_label_enable()
- From: Jeremy Fitzhardinge
- [Xen-devel] [PATCH RFC V2 3/5] jump_label: if a key has already been initialized, don't nop it out
- From: Jeremy Fitzhardinge
- [Xen-devel] Re: [PATCH RFC V2 3/5] jump_label: if a key has already been initialized, don't nop it out
- [Xen-devel] Re: [PATCH RFC V2 3/5] jump_label: if a key has already been initialized, don't nop it out
- From: Jeremy Fitzhardinge
- [Xen-devel] Re: [PATCH RFC V2 3/5] jump_label: if a key has already been initialized, don't nop it out
- [Xen-devel] Re: [PATCH RFC V2 3/5] jump_label: if a key has already been initialized, don't nop it out
- [Xen-devel] Re: [PATCH RFC V2 3/5] jump_label: if a key has already been initialized, don't nop it out
- From: Jeremy Fitzhardinge
- [Xen-devel] Re: [PATCH RFC V2 3/5] jump_label: if a key has already been initialized, don't nop it out
- [Xen-devel] Re: [PATCH RFC V2 3/5] jump_label: if a key has already been initialized, don't nop it out
- From: Jeremy Fitzhardinge
- [Xen-devel] Re: [PATCH RFC V2 3/5] jump_label: if a key has already been initialized, don't nop it out
- [Xen-devel] Re: [PATCH RFC V2 3/5] jump_label: if a key has already been initialized, don't nop it out
- [Xen-devel] Re: [PATCH RFC V2 3/5] jump_label: if a key has already been initialized, don't nop it out
- From: Jeremy Fitzhardinge
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