From: Stephen Hemminger <shemminger@osdl.org>
To: David Miller <davem@davemloft.net>
Cc: dada1@cosmosbay.com, netdev@vger.kernel.org
Subject: Re: [PATCH] [NET] Size listen hash tables using backlog hint
Date: Wed, 18 Oct 2006 21:54:08 -0700 [thread overview]
Message-ID: <453704F0.4010707@osdl.org> (raw)
In-Reply-To: <20061018.203109.63997999.davem@davemloft.net>
David Miller wrote:
> From: Eric Dumazet Hi <dada1@cosmosbay.com>
> Date: Tue, 17 Oct 2006 14:58:37 +0200
>
>
>> reqsk_queue_alloc() goal is to use a power of two size for the whole
>> listen_sock structure, to avoid wasting memory for large backlogs,
>> meaning the hash table nr_table_entries is not anymore a power of
>> two. (Hence one AND (nr_table_entries - 1) must be replaced by
>> MODULO nr_table_entries)
>>
>
> Modulus can be very expensive for some small/slow cpus. Please round
> down to a power-of-2 instead of up if you think the wastage really
> matters.
>
Reminds me, anyone know why GCC is too stupid to convert modulus of a
constant power of 2
into a mask operation?
next prev parent reply other threads:[~2006-10-19 4:54 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-10-17 0:53 [PATCH] Bound TSO defer time (resend) John Heffner
2006-10-17 3:20 ` Stephen Hemminger
2006-10-17 4:18 ` John Heffner
2006-10-17 5:35 ` David Miller
2006-10-17 12:22 ` John Heffner
2006-10-19 3:39 ` David Miller
2006-10-17 12:58 ` [PATCH] [NET] Size listen hash tables using backlog hint Eric Dumazet Hi
2006-10-18 7:38 ` [PATCH] [NET] inet_peer : group together avl_left, avl_right, v4daddr to speedup lookups on some CPUS Eric Dumazet
2006-10-18 16:35 ` [PATCH] [NET] reduce per cpu ram used for loopback stats Eric Dumazet
2006-10-18 17:00 ` [PATCH, resent] " Eric Dumazet
2006-10-19 3:53 ` David Miller
2006-10-19 3:53 ` [PATCH] " David Miller
2006-10-19 3:44 ` [PATCH] [NET] inet_peer : group together avl_left, avl_right, v4daddr to speedup lookups on some CPUS David Miller
2006-10-19 10:57 ` Eric Dumazet
2006-10-19 15:45 ` [PATCH] [NET] One NET_INC_STATS() could be NET_INC_STATS_BH in tcp_v4_err() Eric Dumazet
2006-10-20 7:22 ` David Miller
2006-10-20 14:21 ` Arnaldo Carvalho de Melo
2006-10-20 7:28 ` [PATCH] [NET] inet_peer : group together avl_left, avl_right, v4daddr to speedup lookups on some CPUS David Miller
2006-10-19 3:31 ` [PATCH] [NET] Size listen hash tables using backlog hint David Miller
2006-10-19 4:54 ` Stephen Hemminger [this message]
2006-10-19 5:08 ` David Miller
2006-10-19 5:12 ` Eric Dumazet
2006-10-19 6:12 ` David Miller
2006-10-19 6:34 ` Eric Dumazet
2006-10-19 6:57 ` David Miller
2006-10-19 8:29 ` Eric Dumazet
2006-10-19 8:41 ` David Miller
2006-10-19 9:11 ` Eric Dumazet
2006-10-19 9:27 ` Eric Dumazet
2006-10-20 7:27 ` David Miller
2006-10-18 15:37 ` [PATCH] Bound TSO defer time (resend) Andi Kleen
2006-10-18 16:40 ` Stephen Hemminger
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