Re: [PATCH net-next] softirq: reduce latencies

From: Namhyung Kim
Date: Fri Jan 04 2013 - 00:16:45 EST


On Thu, 03 Jan 2013 14:41:15 -0800, Eric Dumazet wrote:
> On Thu, 2013-01-03 at 12:46 -0800, Andrew Morton wrote:
>> Can this change cause worsened latencies in some situations? Say there
>> are a large number of short-running actions queued. Presently we'll
>> dispatch ten of them and return. With this change we'll dispatch many
>> more of them - however many consume 2ms. So worst-case latency
>> increases from "10 * not-much" to "2 ms".
> I tried to reproduce such workload but couldnt. 2 ms (or more exactly 1
> to 2 ms given the jiffies/HZ granularity) is about the time needed to
> process 1000 frames on current hardware.

Probably a silly question:

Why not using ktime rather than jiffies for this?

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