netdev - Re: [DST]: shrinks sizeof(struct rtable) by 64 bytes on x86

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Date:	Tue, 22 Jan 2008 06:18:52 -0800 (PST)
From:	David Miller <davem@...emloft.net>
To:	dada1@...mosbay.com
Cc:	netdev@...r.kernel.org
Subject: Re: [DST]: shrinks sizeof(struct rtable) by 64 bytes on x86_64

From: Eric Dumazet <dada1@...mosbay.com>
Date: Tue, 22 Jan 2008 11:50:06 +0100

> On x86_64, sizeof(struct rtable) is 0x148, which is rounded up to 0x180
> bytes by SLAB allocator.
> 
> We can reduce this to exactly 0x140 bytes, without alignment overhead,
> and store 12 struct rtable per PAGE instead of 10.
> 
> rate_tokens is currently defined as an "unsigned long", while its content
> should not exceed 6*HZ. It can safely be converted to an unsigned int.
> 
> Moving tclassid right after rate_tokens to fill the 4 bytes hole permits
> to save 8 bytes on 'struct dst_entry', which finally permits to save 8
> bytes on 'struct rtable'
> 
> Signed-off-by: Eric Dumazet <dada1@...mosbay.com>

Thanks for doing this work Eric.

Patch applied.
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