[PATCHSET 0/9] Batched completions

Hi,

We now do decent batching of allocations for submit, but we still
complete requests individually. This costs a lot of CPU cycles.

This patchset adds support for collecting requests for completion,
and then completing them as a batch. This includes things like freeing
a batch of tags.

A few rough edges in this patchset, but sending it out for comments
so I can whip it into an upstreamable thing. As per patch 8, the
wins here are pretty massive - 8-10% improvement in the peak IOPS.

-- 
Jens Axboe