On Mon, Dec 01, 2014 at 01:02:58PM +0100, Cornelia Huck wrote:

On Mon, 1 Dec 2014 13:46:45 +0200
"Michael S. Tsirkin" [off-list ref] wrote:

quoted

On Mon, Dec 01, 2014 at 12:33:15PM +0100, Cornelia Huck wrote:

quoted

On Mon, 1 Dec 2014 11:26:58 +0200
"Michael S. Tsirkin" [off-list ref] wrote:

quoted

For some places on data path, it might be worth it
to cache the correct value e.g. as part of device
structure. This replaces a branch with a memory load,
so the gain would have to be measured, best done
separately?

I think we'll want to do some measuring once the basic structure is
in place anyway.

What's meant by in place here?

That this patchset is ready :)

Also it's ready to the level where benchmarking is possible, right?  I
don't think you should wait until we finish polishing up commit
messages.

quoted

quoted

We should make sure that e.g. s390 only takes minor
hit due to all that swapping that is needed for standard-compliant
devices. Caching the value might certainly help in some paths.

Well, this is queued in linux-next for 3.19, so
now's the time to do it :)

So much to do, so little time...

I'm still feeling a bit uncomfortable with some of the changes
(virtio-scsi etc.) as I have not been able to test them yet (as there's
no converted qemu for these yet). The virtio-net and virtio-blk changes
seem sane, though, and virtio-ccw should be fine as well.

OTOH, it's not like we're introducing new external interfaces, so later
rework should be fine.