From: David Miller <davem@davemloft.net>
To: brking@linux.vnet.ibm.com
Cc: rick.jones2@hp.com, cascardo@linux.vnet.ibm.com,
netdev@vger.kernel.org, yevgenyp@mellanox.co.il,
ogerlitz@mellanox.com, amirv@mellanox.com,
leitao@linux.vnet.ibm.com, klebers@linux.vnet.ibm.com
Subject: Re: [PATCH] mlx4_en: map entire pages to increase throughput
Date: Tue, 17 Jul 2012 13:20:19 -0700 (PDT) [thread overview]
Message-ID: <20120717.132019.1633094178309164749.davem@davemloft.net> (raw)
In-Reply-To: <5005C6A0.50002@linux.vnet.ibm.com>
From: Brian King <brking@linux.vnet.ibm.com>
Date: Tue, 17 Jul 2012 15:10:08 -0500
> On 07/17/2012 01:17 PM, Rick Jones wrote:
>> On 07/16/2012 10:29 PM, David Miller wrote:
>>> From: Rick Jones <rick.jones2@hp.com> Date: Mon, 16 Jul 2012
>>> 10:27:57 -0700
>>>
>>>> That seems rather extraordinarily low - Power7 is supposed to be
>>>> a rather high performance CPU. The last time I noticed
>>>> O(3Gbit/s) on 10G for bulk transfer was before the advent of
>>>> LRO/GRO - that was in the x86 space though. Is mapping really
>>>> that expensive with Power7?
>>>
>>> Unfortunately, IOMMU mappings are incredibly expensive. I see
>>> effects like this on Sparc too.
>>
>> OK, so that has caused some dimm memory to get a small refresh - it
>> ends up being akin to if not actually a PIO yes? I recall schemes in
>> drivers in other stacks whereby "small" packets were copied because
>> it was cheaper to allocate/copy then it was to remap.
>
> On Power it ends up being an hcall to the hypervisor
This is true on sparc64 niagara systems as well.
next prev parent reply other threads:[~2012-07-17 20:20 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-16 17:01 [PATCH] mlx4_en: map entire pages to increase throughput Thadeu Lima de Souza Cascardo
2012-07-16 17:27 ` Rick Jones
2012-07-16 19:06 ` Thadeu Lima de Souza Cascardo
2012-07-16 19:06 ` Thadeu Lima de Souza Cascardo
2012-07-16 19:42 ` Rick Jones
2012-07-16 19:42 ` Rick Jones
2012-07-16 20:36 ` Or Gerlitz
2012-07-16 20:36 ` Or Gerlitz
2012-07-16 20:43 ` Or Gerlitz
2012-07-16 20:43 ` Or Gerlitz
2012-07-16 20:57 ` Thadeu Lima de Souza Cascardo
2012-07-16 20:57 ` Thadeu Lima de Souza Cascardo
2012-07-18 14:59 ` Or Gerlitz
2012-07-18 14:59 ` Or Gerlitz
2012-07-16 20:47 ` Thadeu Lima de Souza Cascardo
2012-07-16 20:47 ` Thadeu Lima de Souza Cascardo
2012-07-16 21:08 ` Rick Jones
2012-07-16 21:08 ` Rick Jones
2012-07-17 5:29 ` David Miller
2012-07-17 12:42 ` David Laight
2012-07-17 12:50 ` David Miller
2012-07-17 13:36 ` David Laight
2012-07-17 13:46 ` David Miller
2012-07-17 13:50 ` Eric Dumazet
2012-07-17 18:17 ` Rick Jones
2012-07-17 20:10 ` Brian King
2012-07-17 20:20 ` David Miller [this message]
2012-07-19 17:53 ` David Miller
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