Date: Tue, 6 Oct 2009 20:17:13 +0200
From: Jens Axboe <jens.axboe@oracle.com>
To: Nikanth Karthikesan <knikanth@suse.de>
Cc: Corrado Zoccolo <czoccolo@gmail.com>,
       Linux-Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [RESEND][PATCH linux-2.6-block#for-linus]  Seperate read and
	write statistics of in_flight requests v2
Message-ID: <20091006181713.GC5216@kernel.dk>
References: <200910061855.48502.knikanth@suse.de>
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On Tue, Oct 06 2009, Nikanth Karthikesan wrote:
> [Sorry, resending as the previous mail was word-wrapped]
> 
> Commit a9327cac440be4d8333bba975cbbf76045096275 added seperate read
> and write statistics of in_flight requests. And exported the number
> of read and write requests in progress seperately through sysfs.
> 
> But  Corrado Zoccolo <czoccolo@gmail.com> reported getting strange
> output from "iostat -kx 2". Global values for service time and
> utilization were garbage. For interval values, utilization was always
> 100%, and service time is higher than normal.
> 
> So this was reverted by commit 0f78ab9899e9d6acb09d5465def618704255963b
> 
> The problem was in part_round_stats_single(), I missed the following:
>         if (now == part->stamp)
>                 return;
> 
> -       if (part->in_flight) {
> +       if (part_in_flight(part)) {
>                 __part_stat_add(cpu, part, time_in_queue,
>                                 part_in_flight(part) * (now - part->stamp));
>                 __part_stat_add(cpu, part, io_ticks, (now - part->stamp));
> 
> With this chunk included, the reported regression gets fixed.

Thanks, applied.

-- 
Jens Axboe

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