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 13:42:04 +0100
From:	"David Laight" <David.Laight@...LAB.COM>
To:	"David Miller" <davem@...emloft.net>, <rick.jones2@...com>
Cc:	<cascardo@...ux.vnet.ibm.com>, <netdev@...r.kernel.org>,
	<yevgenyp@...lanox.co.il>, <ogerlitz@...lanox.com>,
	<amirv@...lanox.com>, <brking@...ux.vnet.ibm.com>,
	<leitao@...ux.vnet.ibm.com>, <klebers@...ux.vnet.ibm.com>
Subject: RE: [PATCH] mlx4_en: map entire pages to increase throughput

> > 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.

Would there be any mileage in permanently allocating IOMMU
virtual address to the ring entries, then 'just' assigning
the correct physical address during rx/tx setup?

A long time ago it used to be much faster on sparc systems
to receive into a permanently mapped buffer area and then
do a maximally aligned copy into the actual rx buffer.

	David



--
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