linux-kernel - Re: [PATCH v2] cfq-iosched: convert group idle time to jiffies

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Date:	Tue, 29 Dec 2015 21:25:36 +0100
From:	Alexandru Moise <00moses.alexander00@...il.com>
To:	Jens Axboe <axboe@...nel.dk>
Cc:	linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] cfq-iosched: convert group idle time to jiffies

On Tue, Dec 29, 2015 at 01:19:57PM -0700, Jens Axboe wrote:
> On 12/29/2015 01:16 PM, Alexandru Moise wrote:
> >This patch refers to Jens Axboe's change way back in 2006:
> >7b14e3b52 cfq-iosched: slice expiry fixups
> >
> >In this patch he fixed a potential timer race condition by delaying
> >idle_slice_timer by the slice_idle time value.
> >
> >Today this timer is delayed by either slice_idle or group_idle time
> >values, which on my system, and according to
> >Documentation/block/cfq-iosched.txt the default value for group_idle
> >is 8ms.
> >
> >Since the time given by group_idle is supposed to be in milliseconds
> >we should convert that value from milliseconds to jiffies before
> >adding it to jiffies variable and setting our timer.
> 
> Again, the slice idle values are stored in jiffies, there's no need
> to convert. I think you are missing the fact that we display the
> value in msecs, and convert when displaying/storing through sysfs.
> 
> -- 
> Jens Axboe
> 

Damn, yeah just saw the conversion in the STORE/SHOW_FUNCTION macros.

My bad..
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