From: Tom Parkin <tparkin@katalix.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Rick Jones <rick.jones2@hp.com>,
Ben Greear <greearb@candelatech.com>,
Stephen Hemminger <shemminger@vyatta.com>,
netdev@vger.kernel.org, David.Laight@ACULAB.COM,
James Chapman <jchapman@katalix.com>
Subject: Re: [PATCH v2] l2tp: use per-cpu variables for u64_stats updates
Date: Thu, 28 Jun 2012 09:24:58 +0100 [thread overview]
Message-ID: <20120628082457.GA2507@raven> (raw)
In-Reply-To: <1340859654.26242.201.camel@edumazet-glaptop>
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On Thu, Jun 28, 2012 at 07:00:54AM +0200, Eric Dumazet wrote:
> [1] : LLTX drivers case
> since ndo_start_xmit() can be run concurrently by many cpus, safely
> updating an "unsigned long" requires additional hassle :
>
> 1) Use of a spinlock to protect the update.
> 2) Use atomic_long_t instead of "unsigned long"
> 3) Use percpu data
>
> 3) is overkill for devices with light traffic, because it consumes lot
> of RAM on machines with 2048 possible cpus, _and_ the reader must fold
> the data of all possible values.
Thanks Eric.
So am I right in thinking that a v3 patch which uses atomic_long_t for
the statistics would be the correct way forwards?
--
Tom Parkin
Katalix Systems Ltd
http://www.katalix.com
Catalysts for your Embedded Linux software development
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next prev parent reply other threads:[~2012-06-28 8:25 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-27 12:00 [PATCH v2] l2tp: use per-cpu variables for u64_stats updates Tom Parkin
2012-06-27 19:03 ` Eric Dumazet
2012-06-27 20:21 ` Rick Jones
2012-06-27 20:39 ` Eric Dumazet
2012-06-27 20:50 ` Stephen Hemminger
2012-06-27 20:58 ` Ben Greear
2012-06-27 21:20 ` Eric Dumazet
2012-06-27 21:31 ` Ben Greear
2012-06-27 21:35 ` Eric Dumazet
2012-06-27 23:01 ` Rick Jones
2012-06-27 23:09 ` David Miller
2012-06-27 23:39 ` Rick Jones
2012-06-28 5:00 ` Eric Dumazet
2012-06-28 8:24 ` Tom Parkin [this message]
2012-06-28 8:46 ` David Laight
2012-06-28 18:17 ` Ben Hutchings
2012-06-27 21:32 ` Eric Dumazet
2012-06-27 21:40 ` Ben Greear
2012-06-27 21:50 ` Eric Dumazet
2012-06-27 21:00 ` Rick Jones
2012-06-27 22:21 ` David Miller
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