netdev - Re: [PATCH net-next] dql: dql_queued() should write first to reduce bus transactions

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20140926104732.625b4141@redhat.com>
Date:	Fri, 26 Sep 2014 10:47:32 +0200
From:	Jesper Dangaard Brouer <brouer@...hat.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Tom Herbert <therbert@...gle.com>,
	Linux Netdev List <netdev@...r.kernel.org>,
	"David S. Miller" <davem@...emloft.net>,
	Alexander Duyck <alexander.h.duyck@...el.com>,
	Toke Høiland-Jørgensen 
	<toke@...e.dk>, Florian Westphal <fw@...len.de>,
	Jamal Hadi Salim <jhs@...atatu.com>,
	Dave Taht <dave.taht@...il.com>,
	John Fastabend <john.r.fastabend@...el.com>,
	Daniel Borkmann <dborkman@...hat.com>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	brouer@...hat.com
Subject: Re: [PATCH net-next] dql: dql_queued() should write first to reduce
 bus transactions

On Thu, 25 Sep 2014 23:04:56 -0700
Eric Dumazet <eric.dumazet@...il.com> wrote:

[...]
> 
> It turned out the problem was caused by compiler trying to be
> smart, but involving a bad MESI transaction :
>
[...] 
> 
> I got an incredible 10 % gain [1] by making sure cpu do not attempt
> to get the cache line in Shared mode, but directly requests for
> ownership.
[...]
> 
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> ---

I'm very impressed - thank you Eric for finding this!!!

Acked-by: Jesper Dangaard Brouer <brouer@...hat.com>

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Sr. Network Kernel Developer at Red Hat
  Author of http://www.iptv-analyzer.org
  LinkedIn: http://www.linkedin.com/in/brouer
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html