Re: [PATCH 00/14] introduce the BFQ-v0 I/O scheduler as an extra scheduler
From: Bart Van Assche
Date: Wed Oct 26 2016 - 11:05:35 EST
On 10/26/2016 04:34 AM, Jan Kara wrote:
On Wed 26-10-16 03:19:03, Christoph Hellwig wrote:
Just as last time:
big NAK for introducing giant new infrastructure like a new I/O scheduler
for the legacy request structure.
Please direct your engergy towards blk-mq instead.
Christoph, we will probably talk about this next week but IMO rotating
disks and SATA based SSDs are going to stay with us for another 15 years,
likely more. For them blk-mq is no win, relatively complex IO scheduling
like CFQ or BFQ does is a big win for them in some cases. So I think IO
scheduling (and thus place for something like BFQ) is going to stay with us
for quite a long time still. So are we going to add hooks in blk-mq to
support full-blown IO scheduling at least for single queue devices? Or how
else do we want to support that HW?
Hello Jan,
Having two versions (one for non-blk-mq, one for blk-mq) of every I/O
scheduler would be a maintenance nightmare. Has anyone already analyzed
whether it would be possible to come up with an API for I/O schedulers
that makes it possible to use the same I/O scheduler for both blk-mq and
the traditional block layer?
Bart.