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From: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
To: David Dillow <dillowda-1Heg1YXhbW8@public.gmane.org>
Cc: Or Gerlitz <ogerlitz-smomgflXvOZWk0Htik3J/w@public.gmane.org>,
	linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Roland Dreier <rdreier-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org>,
	Eli Cohen <eli-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
Subject: Re: IB: increase DMA max_segment_size on Mellanox hardware
Date: Mon, 17 Jan 2011 22:22:29 -0700	[thread overview]
Message-ID: <20110118052229.GC2691@obsidianresearch.com> (raw)
In-Reply-To: <1295318783.3051.81.camel-1q1vX8mYZiGLUyTwlgNVppKKF0rrzTr+@public.gmane.org>

On Mon, Jan 17, 2011 at 09:46:23PM -0500, David Dillow wrote:

> To be sure, this is not going to be a huge efficiency gain, but it does
> reduce CPU usage and raises the largest possible IO size with the
> default srp_sg_tablesize of 12 from 768 KB to some 24 GB. Not that we'd
> likely need that large of a request or be able to allocate 12 2GB
> contiguous memory areas, of course.

AH! So this is why.. I went to some trouble to add huge page support
to some code expecting to get bigger/more consisent SRP IOs and didn't
quite get that result :)

Jason
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  parent reply	other threads:[~2011-01-18  5:22 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-01-17  2:09 IB: increase DMA max_segment_size on Mellanox hardware David Dillow
     [not found] ` <1295230184.2574.26.camel-1q1vX8mYZiGLUyTwlgNVppKKF0rrzTr+@public.gmane.org>
2011-01-17 11:16   ` Or Gerlitz
     [not found]     ` <4D342510.80701-smomgflXvOZWk0Htik3J/w@public.gmane.org>
2011-01-18  2:46       ` David Dillow
     [not found]         ` <1295318783.3051.81.camel-1q1vX8mYZiGLUyTwlgNVppKKF0rrzTr+@public.gmane.org>
2011-01-18  5:22           ` Jason Gunthorpe [this message]
2011-01-18  7:16           ` Or Gerlitz
     [not found]             ` <4D353E5E.2020500-smomgflXvOZWk0Htik3J/w@public.gmane.org>
2011-01-18 12:25               ` David Dillow
     [not found]                 ` <1295353524.3051.121.camel-1q1vX8mYZiGLUyTwlgNVppKKF0rrzTr+@public.gmane.org>
2011-01-18 18:01                   ` Jason Gunthorpe
2011-01-20 10:14                   ` Or Gerlitz
     [not found]                     ` <4D380AF2.4010905-smomgflXvOZWk0Htik3J/w@public.gmane.org>
2011-01-20 12:15                       ` David Dillow
     [not found]                         ` <1295525737.22825.24.camel-1q1vX8mYZiGLUyTwlgNVppKKF0rrzTr+@public.gmane.org>
2011-01-24 15:18                           ` Or Gerlitz
     [not found]                             ` <4D3D9845.4050803-smomgflXvOZWk0Htik3J/w@public.gmane.org>
2011-01-24 19:36                               ` David Dillow
     [not found]                                 ` <1295897819.29946.17.camel-FqX9LgGZnHWDB2HL1qBt2PIbXMQ5te18@public.gmane.org>
2011-02-17  1:06                                   ` David Dillow
     [not found]                                     ` <1297904810.8833.44.camel-FqX9LgGZnHWDB2HL1qBt2PIbXMQ5te18@public.gmane.org>
2011-03-16 19:17                                       ` Or Gerlitz
2011-01-20 10:18           ` Or Gerlitz
     [not found]             ` <4D380BDC.5080002-smomgflXvOZWk0Htik3J/w@public.gmane.org>
2011-01-20 12:25               ` David Dillow
2011-03-22  8:01   ` Or Gerlitz
     [not found]     ` <4D885748.6060600-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
2011-03-22 12:51       ` David Dillow

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