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

From: Jens Axboe
Date: Tue Dec 29 2015 - 15:20:09 EST


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

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