Re: [GIT PULL] core block IO bits for 3.8

[Jeff Moyer <jmoyer@redhat.com>]

Jens Axboe <axboe@kernel.dk> writes:

> On 2012-12-17 18:00, Tejun Heo wrote:
>> On Mon, Dec 17, 2012 at 11:06:39AM -0500, Jeff Moyer wrote:
>>> Jens Axboe <axboe@kernel.dk> writes:
>>>
>>>> - Export control of bdi flusher thread CPU mask and default to using the
>>>>   home node (if known) from Jeff.
>>>
>>> I certainly wouldn't mind this going in, but I think Tejun NACKed this
>>> patch.  Tejun?
>> 
>> Hmm... yeah, I would much prefer if this doesn't go in this time.  I
>> think we need something more generic for threadpools w/ scheduling
>> restrictions.  It would be possible to retrofit so that the interface
>> eventually matches but given that this feature isn't an immediate
>> must-have thing, I think it would be better to not do this right now.
>
> OK, if you have something generic for threadpools in mind, we can wait
> with this one. I just thought that a "real" interface was nicer than
> manual setting, especially since the flusher threads come and go. Then
> you'd need some udev hook to get it set, not even sure how easy that
> would be with the weird linkage.
>
> Jeff, lets default to the node mask at least. Can you resend a patch
> that doesn't add the API, but just defaults to setting the affinity to
> the cpu mask of the home node?

Well, it turns out that the numa node is always -1, since bdi devices
always have a null parent.  I have a patch set to clean that up, but it
depends on my other numa patches in the scsi area that will hopefully
go in 3.9.

> Linus, how do you want to handle this? I can do a revert and re-send a
> pull.

For now, I think it would be cleanest if we just reverted the change.

Cheers,
Jeff