linux-kernel - Re: [PATCH net-next 0/2] net: lls cleanup patches

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Message-Id: <20130701.140833.1705666564717621661.davem@davemloft.net>
Date:	Mon, 01 Jul 2013 14:08:33 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	eliezer.tamir@...ux.intel.com
Cc:	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	willemb@...gle.com, erdnetdev@...il.com, andi@...stfloor.org,
	hpa@...or.com, devel-lists@...yps.com, eliezer@...ir.org.il
Subject: Re: [PATCH net-next 0/2] net: lls cleanup patches

From: Eliezer Tamir <eliezer.tamir@...ux.intel.com>
Date: Fri, 28 Jun 2013 15:59:18 +0300

> Here are two cleanup patches.
> 
> 1. fix warning from debug_smp_processor_id().
> - reported by Cody P Schafer.
> 
> 2. avoid calling sched_clock() in select and poll when lls is disabled.
> - reported by Andi Kleen.
> 
> Thanks to everyone for their comments.

Applied, but like Ben said perhaps you want to remember the last cpu you
got the sched_clock() measurement from and abort the ll poll if it changes
on you instead of using a comparison between two cpus.

But then again, since preemption is enabled, the cpu could change
back and forth during the sched_clock() call, so you wouldn't be able
to reliably detect this anyways.

In the grand scheme of things all of this probably doesn't matter at
all.
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