David Miller wrote:
From: John Heffner <[EMAIL PROTECTED]>
Date: Tue, 17 Oct 2006 00:18:33 -0400
Stephen Hemminger wrote:
On Mon, 16 Oct 2006 20:53:20 -0400 (EDT)
John Heffner <[EMAIL PROTECTED]> wrote:
This patch limits the amount of time you will defer sending a TSO segment
to less than two clock ticks, or the time between two acks, whichever is
longer.
Okay, but doing any timing on clock ticks makes the behavior dependent
on the value of HZ which doesn't seem desirable. Should this be based
on RTT or a real-time values?
It would be nice to use a high res clock so you don't depend on HZ, but
this is still expensive on most SMP arch's as I understand it.
Right so we do need to use a jiffies based solution.
Since HZ is variable, I have a feeling that the thing to do here
is pick some timeout in msec. Then replace the "2 clock ticks"
with some msec_to_jiffies() calls, bottoming out at 1 jiffie.
How does that sound?
That's actually how I originally coded it. :) But then it occurred to
me that if you've already been waiting for a full clock tick, the
marginal CPU savings of waiting longer will not be great. Which is why
I chose the value of 2 ticks so you're guaranteed to have waited at
least one full tick.
-John
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