Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1299060

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

Show all headers | View raw

On 12/28/2015 06:08 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 both is 8ms.
>
> Since the time given by either variables 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.
>
> In my obervations the area is really active as I've seen that function
> get called a lot for each device on my btrfs raid setup during btrfs
> check. I've also timed the btrfs check before and after applying the
> patch and I might've noticed a very slight improvement in execution
> time but the numbers vary too much for me to post any believable
> numbers (10 milliseconds difference at most on average).

cfqd->cfq_slice_idle is in jiffies, it's not in msecs.

-- 
Jens Axboe

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH] cfq-iosched: convert slice idle time to jiffies Alexandru Moise <00moses.alexander00@gmail.com> - 2015-12-29 02:10 +0100
  Re: [PATCH] cfq-iosched: convert slice idle time to jiffies Jens Axboe <axboe@kernel.dk> - 2015-12-29 18:20 +0100
    Re: [PATCH] cfq-iosched: convert slice idle time to jiffies Alexandru Moise <00moses.alexander00@gmail.com> - 2015-12-29 18:40 +0100

csiph-web