Re: [patch 00/20] timer: Refactor the timer wheel

[Eric Dumazet]

On Mon, Jun 13, 2016 at 1:40 AM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
> The current timer wheel has some drawbacks:

...

> This series has also preparatory patches for changing the NOHZ timer handling
> from the current push to a pull model. Currently we decide at timer enqueue
> time on which cpu we queue the timer. This is exceptionally silly because
> there is no way to predict at enqueue time which cpu will be idle when the
> timer expires. Given the fact that most timers are canceled or rearmed before
> expiry this is even more silly. We trade a expensive decision and cross cpu
> access for a very doubtful benefit.
>

Also many TCP timers are armed from softirq handler interrupting idle task,
so scheduler believes current cpu is idle .

This patch series is really nice Thomas.