linux-kernel - Re: [PATCH 3/8] blk-iocost: Trace vtime_base_rate instead of vtime

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Message-ID: <Y02nBcwomc+9xZ+l@slm.duckdns.org>
Date:   Mon, 17 Oct 2022 09:03:33 -1000
From:   Tejun Heo <tj@...nel.org>
To:     Kemeng Shi <shikemeng@...wei.com>
Cc:     axboe@...nel.dk, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/8] blk-iocost: Trace vtime_base_rate instead of
 vtime_rate

On Mon, Oct 17, 2022 at 10:00:06AM +0800, Kemeng Shi wrote:
> Since commit ac33e91e2daca ("blk-iocost: implement vtime loss
> compensation") rename original vtime_base to vtime_base_rate
> and current vtime_base is original vtime_base with compensation.
              ^
              vtime_rate

There are multiple places with the same mistake. Can you please fix the
patch description?

> The current rate showed in tracepoint is mixed with vtime_base
> and vtime_base_rate:
> 1) In function ioc_adjust_base_vrate, the first trace_iocost_ioc_vrate_adj
> shows vtime_base, the second trace_iocost_ioc_vrate_adj shows
> vtime_base_rate.
> 2) In function iocg_activate shows vtime_base by calling
> TRACE_IOCG_PATH(iocg_activate...
> 3) In function ioc_check_iocgs shows vtime_base by calling
> TRACE_IOCG_PATH(iocg_idle...
> 
> Trace vtime_base_rate instead of vtime_rate as:
> 1) Before commit ac33e91e2daca ("blk-iocost: implement vtime loss
> compensation"), the traced rate is without compensation, so still
> show rate without compensation.
> 2) The vtime_base_rate is more stable while vtime_rate heavily depends on
> excess budeget on current period which may change abruptly in next period.
> 
> Signed-off-by: Kemeng Shi <shikemeng@...wei.com>

Other than that,

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

Thanks.

-- 
tejun