From: Bart Van Assche <bvanassche@acm.org>
To: Damien Le Moal <damien.lemoal@wdc.com>,
linux-block@vger.kernel.org, Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCH] block: Remove unnecessary elevator operation checks
Date: Fri, 18 Jun 2021 09:28:33 -0700 [thread overview]
Message-ID: <754f929e-1d72-591c-70c8-836a45940652@acm.org> (raw)
In-Reply-To: <20210618015922.713999-1-damien.lemoal@wdc.com>
On 6/17/21 6:59 PM, Damien Le Moal wrote:
> The insert_requests and dispatch_request elevator operations are
> mandatory for the correct execution of an elevator, and all implemented
> elevators (bfq, kyber and mq-deadline) implement them. As a result,
> there is no need to check for these operations before calling them when
> a queue has an elevator set. This simplifies the code in
> __blk_mq_sched_dispatch_requests() and blk_mq_sched_insert_request().
>
> To avoid out-of-tree elevators to crash the kernel in case of bad
> implementation, add a check in elv_register() to verify that these
> operations are implemented.
>
> A small, probably not significant, IOPS improvement of 0.1% is observed
> with this patch applied (4.117 MIOPS to 4.123 MIOPS, average of 20 fio
> runs doing 4K random direct reads with psync and 32 jobs).
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
prev parent reply other threads:[~2021-06-18 16:28 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-18 1:59 [PATCH] block: Remove unnecessary elevator operation checks Damien Le Moal
2021-06-18 8:52 ` Johannes Thumshirn
2021-06-18 14:52 ` Jens Axboe
2021-06-18 16:28 ` Bart Van Assche [this message]
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