From: Eric Dumazet <dada1@cosmosbay.com>
To: David Miller <davem@davemloft.net>
Cc: bcrl@kvack.org, shemminger@linux-foundation.org, netdev@vger.kernel.org
Subject: Re: [patch 1/4] network dev read_mostly
Date: Thu, 15 Mar 2007 08:42:20 +0100 [thread overview]
Message-ID: <45F8F8DC.3010302@cosmosbay.com> (raw)
In-Reply-To: <20070315.002516.59485075.davem@davemloft.net>
David Miller a écrit :
> From: Eric Dumazet <dada1@cosmosbay.com>
> Date: Thu, 15 Mar 2007 07:28:35 +0100
>
>> One problem with your patch is that all read_always() of pointers are going to
>> use 3 bytes more of code, thus raising icache pressure.
>>
>> 48 b8 c3 08 e8 8c af mov $0x71af8ce808c3,%rax
>> 71 00 00
>>
>> instead of %rip relative addressing
>>
>> 48 8b 05 99 f3 09 00 mov 652185(%rip),%rax
>
> Could we obtain %rip relative addressing with the ELF
> relocation approach I mentioned?
I dont think so, because 32 bits relative to %rip is not enough to cover all
the addresses that a 64bits kernel can use :)
%rip relative addressing works only because all the x86_64 kernel (text+
static/bss data) are in the 0xffffffff80000000 - fffffffffff00000 2^31 quadrant
but vmalloc() range for example is ffffc20000000000 - ffffe1ffffffffff (45 bits)
next prev parent reply other threads:[~2007-03-15 7:42 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-12 21:08 [patch 0/4] more stuff for 2.6.22 Stephen Hemminger
2007-03-12 21:08 ` [patch 1/4] network dev read_mostly Stephen Hemminger
2007-03-12 21:34 ` David Miller
2007-03-13 5:37 ` Eric Dumazet
2007-03-13 21:26 ` [RFC] Get rid of netdev_nit Stephen Hemminger
2007-04-21 0:02 ` David Miller
2007-03-15 2:18 ` [patch 1/4] network dev read_mostly Benjamin LaHaise
2007-03-15 4:54 ` David Miller
2007-03-15 6:28 ` Eric Dumazet
2007-03-15 7:25 ` David Miller
2007-03-15 7:42 ` Eric Dumazet [this message]
2007-03-15 13:17 ` Benjamin LaHaise
2007-03-16 17:03 ` Stephen Hemminger
2007-03-15 15:10 ` Andi Kleen
2007-03-12 21:08 ` [patch 2/4] net: make seq_operations const Stephen Hemminger
2007-03-12 21:34 ` David Miller
2007-03-12 21:08 ` [patch 3/4] net: show bound packet types Stephen Hemminger
2007-03-12 21:35 ` David Miller
2007-03-12 21:08 ` [patch 4/4] tcp: statistics not read_mostly Stephen Hemminger
2007-03-12 21:15 ` David Miller
2007-03-12 21:26 ` Stephen Hemminger
2007-03-12 21:33 ` David Miller
2007-03-13 20:09 ` Andi Kleen
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