linux-kernel - Re: [PATCH V10 0/8] block, bfq: extend bfq to support multi-actuator drives

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Date:   Tue, 13 Dec 2022 16:40:03 +0100
From:   Paolo Valente <paolo.valente@...aro.org>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     linux-block <linux-block@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Arie van der Hoeven <arie.vanderhoeven@...gate.com>,
        Rory Chen <rory.c.chen@...gate.com>,
        Glen Valante <glen.valante@...aro.org>,
        Damien Le Moal <damien.lemoal@...nsource.wdc.com>
Subject: Re: [PATCH V10 0/8] block, bfq: extend bfq to support multi-actuator
 drives

Hi Jens, Damien,
can we consider this for 6.2?

Thanks,
Paolo

> Il giorno 9 dic 2022, alle ore 10:44, Paolo Valente <paolo.valente@...aro.org> ha scritto:
> 
> Hi,
> here is the V10, it differs from V9 in that it applies the
> recommendation by Damien in [2].
> 
> Here is the whole description of this patch series again.  This
> extension addresses the following issue. Single-LUN multi-actuator
> SCSI drives, as well as all multi-actuator SATA drives appear as a
> single device to the I/O subsystem [1].  Yet they address commands to
> different actuators internally, as a function of Logical Block
> Addressing (LBAs). A given sector is reachable by only one of the
> actuators. For example, Seagate’s Serial Advanced Technology
> Attachment (SATA) version contains two actuators and maps the lower
> half of the SATA LBA space to the lower actuator and the upper half to
> the upper actuator.
> 
> Evidently, to fully utilize actuators, no actuator must be left idle
> or underutilized while there is pending I/O for it. To reach this
> goal, the block layer must somehow control the load of each actuator
> individually. This series enriches BFQ with such a per-actuator
> control, as a first step. Then it also adds a simple mechanism for
> guaranteeing that actuators with pending I/O are never left idle.
> 
> See [1] for a more detailed overview of the problem and of the
> solutions implemented in this patch series. There you will also find
> some preliminary performance results.
> 
> Thanks,
> Paolo
> 
> [1] https://www.linaro.org/blog/budget-fair-queueing-bfq-linux-io-scheduler-optimizations-for-multi-actuator-sata-hard-drives/
> [2] https://lore.kernel.org/lkml/20221208104351.35038-1-paolo.valente@linaro.org/T/#t
> 
> Davide Zini (3):
>  block, bfq: split also async bfq_queues on a per-actuator basis
>  block, bfq: inject I/O to underutilized actuators
>  block, bfq: balance I/O injection among underutilized actuators
> 
> Federico Gavioli (1):
>  block, bfq: retrieve independent access ranges from request queue
> 
> Paolo Valente (4):
>  block, bfq: split sync bfq_queues on a per-actuator basis
>  block, bfq: forbid stable merging of queues associated with different
>    actuators
>  block, bfq: move io_cq-persistent bfqq data into a dedicated struct
>  block, bfq: turn bfqq_data into an array in bfq_io_cq
> 
> block/bfq-cgroup.c  |  94 +++----
> block/bfq-iosched.c | 584 ++++++++++++++++++++++++++++++--------------
> block/bfq-iosched.h | 142 ++++++++---
> block/bfq-wf2q.c    |   2 +-
> 4 files changed, 566 insertions(+), 256 deletions(-)
> 
> --
> 2.20.1