netdev - Re: [PATCH 3/6] IPV4 : use xor rather than multiple ands for route compare

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] [day] [month] [year] [list]

Message-Id: <20080410.211746.35006447.yoshfuji@linux-ipv6.org>
Date:	Thu, 10 Apr 2008 21:17:46 +0900 (JST)
From:	YOSHIFUJI Hideaki / 吉藤英明 
	<yoshfuji@...ux-ipv6.org>
To:	davem@...emloft.net
Cc:	shemminger@...tta.com, dada1@...mosbay.com, netdev@...r.kernel.org,
	yoshfuji@...ux-ipv6.org
Subject: Re: [PATCH 3/6] IPV4 : use xor rather than multiple ands for route
 compare

In article <20080410.035618.217931997.davem@...emloft.net> (at Thu, 10 Apr 2008 03:56:18 -0700 (PDT)), David Miller <davem@...emloft.net> says:

> Branch prediction fares very poorly in such cases, and
> therefore it is better to mispredict one branch over
> all the data items in the same cache line than any one
> of several such branches.  The above new sequence gets
> emitted by the compiler as several integer operations and
> one branch.  As long as all the data items are in the
> same cacheline, this is optimal.

Okay, thanks.

--yoshfuji
--
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