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 14:36:11 +0100
From:	"David Laight" <David.Laight@...LAB.COM>
To:	"David Miller" <davem@...emloft.net>
Cc:	<rick.jones2@...com>, <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

> > 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?
> 
> There is a not a one to one mapping between these two entities,
> in particular on the transmit side.
> 
> A transmit packet can have multiple segments, some of which are
> larger than one IOMMU page.

A SMOP :-) TX is probably easier than RX.
Each tx segment will already go into a separate ring entry,
page boundaries could do the same.
The driver will already have to cope with 'too many segments'
(I remember being passed a full sized frame made of a list
of 1-byte message blocks...)

Or allocate enough sequential IOMMU pages for the longest
tx segment for every ring entry - after all that is already
the 'worst case' allocation!

	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