From: William Lee Irwin III <wli@holomorphy.com>
To: Eric Dumazet <dada1@cosmosbay.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
linux kernel <linux-kernel@vger.kernel.org>,
David Miller <davem@davemloft.net>
Subject: Re: [PATCH] MM : alloc_large_system_hash() can free some memory for non power-of-two bucketsize
Date: Sat, 19 May 2007 11:21:23 -0700 [thread overview]
Message-ID: <20070519182123.GD19966@holomorphy.com> (raw)
In-Reply-To: <20070518115454.d3e32f4d.dada1@cosmosbay.com>
On Fri, May 18, 2007 at 11:54:54AM +0200, Eric Dumazet wrote:
> alloc_large_system_hash() is called at boot time to allocate space
> for several large hash tables.
> Lately, TCP hash table was changed and its bucketsize is not a
> power-of-two anymore.
> On most setups, alloc_large_system_hash() allocates one big page
> (order > 0) with __get_free_pages(GFP_ATOMIC, order). This single
> high_order page has a power-of-two size, bigger than the needed size.
> We can free all pages that wont be used by the hash table.
> On a 1GB i386 machine, this patch saves 128 KB of LOWMEM memory.
> TCP established hash table entries: 32768 (order: 6, 393216 bytes)
The proper way to do this is to convert the large system hashtable
users to use some data structure / algorithm other than hashing by
separate chaining.
-- wli
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next prev parent reply other threads:[~2007-05-19 18:21 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-18 9:54 [PATCH] MM : alloc_large_system_hash() can free some memory for non power-of-two bucketsize Eric Dumazet
2007-05-18 18:21 ` Christoph Lameter
2007-05-19 8:37 ` Andrew Morton
2007-05-19 18:07 ` Eric Dumazet
2007-05-19 18:54 ` David Miller, Eric Dumazet
2007-05-19 20:36 ` Eric Dumazet
2007-05-19 18:21 ` William Lee Irwin III [this message]
2007-05-19 18:41 ` Eric Dumazet
2007-05-21 8:11 ` William Lee Irwin III
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