linux-kernel - Re: [PATCH] blk-throttle: don't check whether or not lower limit is valid if CONFIG_BLK_DEV_THROTTLING

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Message-ID: <X8fmsbgvajlCvvLD@mtj.duckdns.org>
Date:   Wed, 2 Dec 2020 14:10:41 -0500
From:   Tejun Heo <tj@...nel.org>
To:     Yu Kuai <yukuai3@...wei.com>
Cc:     axboe@...nel.dk, cgroups@...r.kernel.org,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        yi.zhang@...wei.com, zhangxiaoxu5@...wei.com
Subject: Re: [PATCH] blk-throttle: don't check whether or not lower limit is
 valid if CONFIG_BLK_DEV_THROTTLING_LOW is off

On Thu, Nov 26, 2020 at 11:18:34AM +0800, Yu Kuai wrote:
> blk_throtl_update_limit_valid() will search for descendants to see if
> 'LIMIT_LOW' of bps/iops and READ/WRITE is nonzero. However, they're always
> zero if CONFIG_BLK_DEV_THROTTLING_LOW is not set, furthermore, a lot of
> time will be wasted to iterate descendants.
> 
> Thus do nothing in blk_throtl_update_limit_valid() in such situation.
> 
> Signed-off-by: Yu Kuai <yukuai3@...wei.com>

Acked-by: Tejun Heo <tj@...nel.org>

Thanks.

-- 
tejun