All of lore.kernel.org
 help / color / mirror / Atom feed
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>

[-- Attachment #1: Type: text/plain, Size: 807 bytes --]

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

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 490 bytes --]

  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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20120628082457.GA2507@raven \
    --to=tparkin@katalix.com \
    --cc=David.Laight@ACULAB.COM \
    --cc=eric.dumazet@gmail.com \
    --cc=greearb@candelatech.com \
    --cc=jchapman@katalix.com \
    --cc=netdev@vger.kernel.org \
    --cc=rick.jones2@hp.com \
    --cc=shemminger@vyatta.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.