linux-kernel - Re: [PATCH] block,bfq: Skip tracing hooks if possible

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Message-ID: <c1f10727-fc7a-7ac8-545b-a3a98b06c01f@kernel.dk>
Date:   Wed, 20 Nov 2019 16:11:03 -0700
From:   Jens Axboe <axboe@...nel.dk>
To:     Dmitry Monakhov <dmonakhov@...il.com>, linux-kernel@...r.kernel.org
Cc:     paolo.valente@...aro.org
Subject: Re: [PATCH] block,bfq: Skip tracing hooks if possible

On 11/1/19 7:11 AM, Dmitry Monakhov wrote:
> In most cases blk_tracing is not active, but  bfq_log_bfqq macro
> generate pid_str unconditionally, which result in significant overhead.
> 
> ## Test
> modprobe null_blk
> echo bfq > /sys/block/nullb0/queue/scheduler
> fio --name=t --ioengine=libaio --direct=1 --filename=/dev/nullb0 \
>     --runtime=30 --time_based=1 --rw=write --iodepth=128 --bs=4k
> 
> # Results
> |        | baseline | w/ patch | gain |
> | iops   | 113.19K  | 126.42K  | +11% |

Applied, thanks.

-- 
Jens Axboe