Re: [benchmark] 1% performance overhead of paravirt_ops on native kernels
From: Pekka Enberg
Date: Tue Jun 02 2009 - 14:13:48 EST
Hi Chris,
On Tue, Jun 2, 2009 at 8:03 AM, Chris Mason <chris.mason@xxxxxxxxxx> wrote:
>>> The best place to fix xen is in the kernel.
On Tue, Jun 02, 2009 at 08:22:57AM -0700, Ulrich Drepper wrote:
>> No. The best way to fix things is _on the way into the kernel_.
On Tue, Jun 2, 2009 at 7:20 PM, Chris Mason <chris.mason@xxxxxxxxxx> wrote:
> It all depends on which parts are causing problems. A 1% performance
> hit, under a CONFIG_ that can be disabled? If maintainers are focusing
> on details like this for long term and active projects, we're doing
> something very wrong.
The fact that CONFIG_PARAVIRT can be disabled doesn't really help. As
a matter of fact, I'd argue that one of the primary reasons
CONFIG_SLUB regression is still there is because people can just
disable it and use CONFIG_SLAB instead.
So I think we have some evidence to suggest that people have less
incentive to fix things once something is merged to the kernel. And I
don't mean the authors of the code here but basically _everyone_
involved in kernel development. It usually takes effort from variety
of people to get everything ironed out because, lets face it, we can't
expect a handful of people to test out every configuration let alone
fix them.
Pekka
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/