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Date:   Thu, 28 Apr 2022 13:24:42 +0200
From:   Jan Kara <jack@suse.cz>
To:     Yu Kuai <yukuai3@huawei.com>
Cc:     jack@suse.cz, tj@kernel.org, axboe@kernel.dk,
        paolo.valente@linaro.org, cgroups@vger.kernel.org,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        yi.zhang@huawei.com
Subject: Re: [PATCH -next v4 3/3] block, bfq: do not idle if only one group
 is activated
Message-ID: <20220428112442.m4cx6uc6f4qaicby@quack3.lan>
References: <20220428111907.3635820-1-yukuai3@huawei.com>
 <20220428111907.3635820-4-yukuai3@huawei.com>
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On Thu 28-04-22 19:19:07, Yu Kuai wrote:
> Now that root group is counted into 'num_groups_with_busy_queues',
> 'num_groups_with_busy_queues > 0' is always true in
> bfq_asymmetric_scenario(). Thus change the condition to '> 1'.
> 
> On the other hand, this change can enable concurrent sync io if only
> one group is activated.
> 
> Signed-off-by: Yu Kuai <yukuai3@huawei.com>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  block/bfq-iosched.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
> index 609b4e894684..aeba9001da0b 100644
> --- a/block/bfq-iosched.c
> +++ b/block/bfq-iosched.c
> @@ -844,7 +844,7 @@ static bool bfq_asymmetric_scenario(struct bfq_data *bfqd,
>  
>  	return varied_queue_weights || multiple_classes_busy
>  #ifdef CONFIG_BFQ_GROUP_IOSCHED
> -	       || bfqd->num_groups_with_busy_queues > 0
> +	       || bfqd->num_groups_with_busy_queues > 1
>  #endif
>  		;
>  }
> -- 
> 2.31.1
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR