On 08/03/2010 12:01 PM, Avi Kivity wrote:
You mean, only one class of users cares about the performance of
loading an initrd. However, you've also argued in other threads how
important it is not to break libvirt even if it means we have to do
silly things (like change help text).
So... why is it that libguestfs has to change itself and yet we
should bend over backwards so libvirt doesn't have to change itself?
libvirt is a major user that is widely deployed, and would be
completely broken if we change -help. Changing -help is of no
consequence to us.
libguestfs is a (pardon me) minor user that is not widely used, and
would suffer a performance regression, not total breakage, unless we
add a fw-dma interface. Adding the interface is of consequence to us:
we have to implement live migration and backwards compatibility, and
support this new interface for a long while.
I certainly buy the argument about making changes of little consequence
to us vs. ones that we have to be concerned about long term.
However, I don't think we can objectively differentiate between a
"major" and "minor" user. Generally speaking, I would rather that we
not take the position of "you are a minor user therefore we're not going
to accommodate you".
Regards,
Anthony Liguori
In an ideal world we wouldn't tolerate any regression. The world is
not ideal, so we prioritize.
the -help change scores very high on benfit/cost. fw-dma, much lower.
Note in both cases the long term solution is for the user to move to
another interface (cap reporting, virtio), so adding an interface
which would only be abandoned later by its only user drops the
benfit/cost ratio even further.
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
