netdev - Re: [PATCH v6] net: batch skb dequeueing from softnet input_pkt

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: <1272863834.2173.173.camel@edumazet-laptop>
Date:	Mon, 03 May 2010 07:17:14 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	Andi Kleen <andi@...stfloor.org>,
	David Miller <davem@...emloft.net>, hadi@...erus.ca,
	xiaosuo@...il.com, therbert@...gle.com, shemminger@...tta.com,
	netdev@...r.kernel.org, lenb@...nel.org
Subject: Re: [PATCH v6] net: batch skb dequeueing from softnet
 input_pkt_queue

Le dimanche 02 mai 2010 à 20:50 -0700, Arjan van de Ven a écrit :

> we effectively do that. The thing is that C2 is so low cost normally
> that it's still worth it even at 20k wakeups...
> 
> this is where the bios tells us how "heavy" the states are....
> and 64 usec... is just not very much.

Maybe its low cost, (apparently, it is, since I can reach ~900.000 ipis
on my 16 cores machine) but multiply this by 16 or 32 or 64 cpus, and
clockevents_notify() cost appears to be a killer, all cpus compete on a
single lock.

Maybe this notifier could use RCU ?


--
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