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  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]
Date:	Tue, 3 Jan 2012 12:01:27 -0000
From:	"David Laight" <David.Laight@...LAB.COM>
To:	<pablo@...filter.org>, <netfilter-devel@...r.kernel.org>
Cc:	<davem@...emloft.net>, <netdev@...r.kernel.org>
Subject: RE: [PATCH 06/19] netfilter: nf_conntrack: use atomic64 for accounting counters

 
>  		if (acct) {
> -			spin_lock_bh(&ct->lock);
> -			acct[CTINFO2DIR(ctinfo)].packets++;
> -			acct[CTINFO2DIR(ctinfo)].bytes += skb->len;
> -			spin_unlock_bh(&ct->lock);
> +			atomic64_inc(&acct[CTINFO2DIR(ctinfo)].packets);
> +			atomic64_add(skb->len,
&acct[CTINFO2DIR(ctinfo)].bytes);
>  		}

On a 32bit arch the two atomic64 operations require a locked
bus cycle each. The spin_unlock_bh() may not need one - so
the code may now be slower (modulo lock contention etc).

Probably worth caching &acct[CTINFO2DIR(ctinfo)] in a local,
the compiler probably can't do it itself.

	David


--
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

Powered by blists - more mailing lists