From: Andi Kleen <andi@firstfloor•org>
To: Eric Dumazet <dada1@cosmosbay•com>
Cc: Patrick McHardy <kaber@trash•net>,
"David S. Miller" <davem@davemloft•net>,
Netfilter Developers <netfilter-devel@vger•kernel.org>,
Linux Network Development list <netdev@vger•kernel.org>
Subject: Re: [PATCH] netfilter: unfold two critical loops in ip_packet_match()
Date: Fri, 30 Jan 2009 16:47:33 +0100 [thread overview]
Message-ID: <87ocxox0bu.fsf@basil.nowhere.org> (raw)
In-Reply-To: <4981CBE2.5020306@cosmosbay.com> (Eric Dumazet's message of "Thu, 29 Jan 2009 16:31:46 +0100")
Eric Dumazet <dada1@cosmosbay•com> writes:
> While doing oprofile tests I noticed two loops are not properly unrolled by gcc
That's because nobody passed -funroll-loops. Did you try that for
that file? Likely will need -O2 too
> +static unsigned long ifname_compare(const void *_a, const void *_b, const void *_mask)
> +{
> + const unsigned long *a = (const unsigned long *)_a;
> + const unsigned long *b = (const unsigned long *)_b;
> + const unsigned long *mask = (const unsigned long *)_mask;
> + unsigned long ret;
> +
> + ret = (a[0] ^ b[0]) & mask[0];
> + ret |= (a[1] ^ b[1]) & mask[1];
> + if (IFNAMSIZ > 2 * sizeof(unsigned long))
> + ret |= (a[2] ^ b[2]) & mask[2];
> + if (IFNAMSIZ > 3 * sizeof(unsigned long))
> + ret |= (a[3] ^ b[3]) & mask[3];
That will silently break for IFNAMSIZ >= 4*sizeof(unsigned long)
You should add a dummy loop for that or at least a BUILD_BUG_ON
-Andi
--
ak@linux•intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2009-01-30 15:48 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-26 22:15 32 core net-next stack/netfilter "scaling" Rick Jones
2009-01-26 23:10 ` Eric Dumazet
2009-01-26 23:14 ` Stephen Hemminger
2009-01-26 23:19 ` Rick Jones
2009-01-27 9:10 ` Eric Dumazet
2009-01-27 9:15 ` Patrick McHardy
2009-01-27 11:29 ` Eric Dumazet
2009-01-27 11:37 ` Patrick McHardy
2009-01-27 16:23 ` Eric Dumazet
2009-01-27 17:33 ` Patrick McHardy
2009-01-27 18:02 ` Rick Jones
2009-01-27 19:09 ` Rick Jones
2009-01-27 19:24 ` Rick Jones
2009-01-27 22:17 ` Eric Dumazet
2009-01-27 22:29 ` Rick Jones
2009-01-27 22:34 ` Eric Dumazet
2009-01-27 22:43 ` Rick Jones
2009-01-28 13:55 ` Eric Dumazet
2009-01-28 16:25 ` Patrick McHardy
2009-01-28 17:07 ` Eric Dumazet
2009-01-28 17:34 ` Eric Dumazet
2009-01-29 15:31 ` [PATCH] netfilter: unfold two critical loops in ip_packet_match() Eric Dumazet
2009-01-30 15:47 ` Andi Kleen [this message]
2009-01-30 16:54 ` Eric Dumazet
2009-01-30 17:27 ` Andi Kleen
2009-01-30 17:27 ` Eric Dumazet
2009-01-30 17:50 ` Andi Kleen
2009-02-09 13:41 ` Patrick McHardy
2009-02-18 15:10 ` Eric Dumazet
2009-02-18 15:21 ` Patrick McHardy
2009-02-18 16:33 ` Eric Dumazet
2009-02-18 16:52 ` Patrick McHardy
2009-02-18 17:36 ` [PATCH] netfilter: xt_physdev fixes Eric Dumazet
2009-02-18 18:14 ` Patrick McHardy
2009-02-19 8:00 ` [PATCH] netfilter: unfold two loops in physdev_mt() Eric Dumazet
2009-02-19 8:14 ` [PATCH] netfilter: unfold two loops in ip6_packet_match() Eric Dumazet
2009-02-19 10:19 ` Patrick McHardy
2009-02-19 10:17 ` [PATCH] netfilter: unfold two loops in physdev_mt() Patrick McHardy
2009-02-20 10:02 ` [PATCH] netfilter: unfold two critical loops in ip_packet_match() Eric Dumazet
2009-02-20 10:04 ` Patrick McHardy
2009-02-09 14:57 ` 32 core net-next stack/netfilter "scaling" Patrick McHardy
2009-02-10 18:44 ` Stephen Hemminger
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