netdev - Re: [PATCH] mlx4_en: map entire pages to increase throughput

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 17 Jul 2012 11:17:46 -0700
From:	Rick Jones <rick.jones2@...com>
To:	David Miller <davem@...emloft.net>
CC:	"cascardo@...ux.vnet.ibm.com" <cascardo@...ux.vnet.ibm.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"yevgenyp@...lanox.co.il" <yevgenyp@...lanox.co.il>,
	"ogerlitz@...lanox.com" <ogerlitz@...lanox.com>,
	"amirv@...lanox.com" <amirv@...lanox.com>,
	"brking@...ux.vnet.ibm.com" <brking@...ux.vnet.ibm.com>,
	"leitao@...ux.vnet.ibm.com" <leitao@...ux.vnet.ibm.com>,
	"klebers@...ux.vnet.ibm.com" <klebers@...ux.vnet.ibm.com>
Subject: Re: [PATCH] mlx4_en: map entire pages to increase throughput

On 07/16/2012 10:29 PM, David Miller wrote:
> From: Rick Jones <rick.jones2@...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.

rick jones
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html