Re: [PATCH] blk-mq: Iterate also over sched_tags requests at blk_mq_tagset_iter()

[Christoph Hellwig <hch@lst.de>]

On Sun, Oct 22, 2017 at 09:32:00PM +0300, Sagi Grimberg wrote:
>
>> Currently, blk_mq_tagset_iter() iterate over initial hctx tags only.
>> In case scheduler is used, it doesn't iterate the hctx scheduler tags
>> and the static request aren't been updated.
>> For example, while using NVMe over Fabrics RDMA host, this cause us not to
>> reinit the scheduler requests and thus not re-register all the memory regions
>> during the tagset re-initialization in the reconnect flow.
>
> I think this is a sign that we should cease from embedding memory
> regions on the pre-allocated requests. Its too much resources
> that we waste. In our case, tags are not really cheap given
> that they take a physical HW resource (rdma memory region).
>
> I think we should switch (again) to a pool design instead. I guess its
> time for a generic MR pool that will serve nvmf, xprt, srp, iser and
> friends.

Liks drivers/infiniband/core/mr_pool.c? :)