Re: [RFC] Unify KVM kernel-space and user-space code into a singleproject

From: Avi Kivity
Date: Mon Mar 22 2010 - 08:49:37 EST


On 03/22/2010 01:23 PM, Ingo Molnar wrote:
* Avi Kivity<avi@xxxxxxxxxx> wrote:

IMO the reason perf is more usable than oprofile has less to do with the
kernel/userspace boundary and more do to with effort and attention spent on
the userspace/user boundary.

[...]
If you are interested in the first-hand experience of the people who are doing
the perf work then here it is: by far the biggest reason for perf success and
perf usability is the integration of the user-space tooling with the
kernel-space bits, into a single repository and project.

Please take a look at the kvm integration code in qemu as a fraction of the whole code base.

The very move you are opposing so vehemently for KVM.

I don't want to fracture a working community.

Oprofile went the way you proposed, and it was a failure. It failed not
because it was bad technology (it was pretty decent and people used it), it
was not a failure because the wrong people worked on it (to the contrary, very
capable people worked on it), it was a failure in hindsight because it simply
incorrectly split into two projects which stiffled the progress of each other.

Every project that has some kernel footprint, except perf, is split like that. Are they all failures?

Seems like perf is also split, with sysprof being developed outside the kernel. Will you bring sysprof into the kernel? Will every feature be duplicated in prof and sysprof?

--
error compiling committee.c: too many arguments to function

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