On Tue, Aug 3, 2010 at 7:31 AM, Munehiro Ikeda<m-ikeda@xxxxxxxxxxxxx> wrote:Vivek Goyal wrote, on 08/02/2010 04:58 PM:You will require one more piece and that is support for per cgroup request
descriptors on request queue. With writes, it is so easy to consume those
128 request descriptors.
Yes. Thank you for the comment.
I have two concerns to do that.
(1) technical concern
If there is fixed device-wide limitation and there are so many groups,
the number of request descriptors distributed to each group can be too
few. My only idea for this is to make device-wide limitation flexible,
but I'm not sure if it is the best or even can be allowed.
(2) implementation concern
Now the limitation is done by generic block layer which doesn't know
about grouping. The idea in my head to solve this is to add a new
interface on elevator_ops to ask IO scheduler if a new request can
We have already done the work of forward porting the request
descriptor patch that Vivek had in his earlier patch sets. We also
taken care of the two concerns you have mentioned above. We have been
testing it, and getting good numbers. So if you want, I can send the
patch your way so it can be included in this same patch series.