From: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
To: Or Gerlitz <or.gerlitz-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Roland Dreier <roland-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
Or Gerlitz <ogerlitz-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>,
linux-rdma <linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Vladimir Sokolovsky
<vlad-VPRAkNaXOzVS1MOuV/RT9w@public.gmane.org>
Subject: Re: [PATCH] mlx4: allow for 4K mtu configuration of IB ports
Date: Wed, 25 May 2011 16:07:05 -0600 [thread overview]
Message-ID: <20110525220705.GG12525@obsidianresearch.com> (raw)
In-Reply-To: <BANLkTinT5OJdP38Xq=PCtx1wgxDhjVfndA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
On Thu, May 26, 2011 at 12:46:20AM +0300, Or Gerlitz wrote:
> > I mean is there anyone who really uses >4 VLs? ?Presumably the
> > HW designers didn't think so, because they limited HW to 4 VLs with 4K MTU.
>
> I'm not sure if 4 VLs are enough for all the topologies / algorithms I
> mentioned above, so I do prefer to leave an option to run with eight
> VLs. As for the HW designers comment, its always good to look
> forward
Routing algorithms only need VLs on interswitch links, not on HCA to
switch links. The only use of the HCA to switch VLs is for QoS. Mesh
topologies can usually be routed with only two VLs, but you need alot
of SLs to make that work.
IMHO it would be much nicer if the SM could control and set this
choice, but since the spec doesn't have a provision for this I'm not
sure what to suggest there..
Jason
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next prev parent reply other threads:[~2011-05-25 22:07 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-25 12:10 [PATCH] mlx4: allow for 4K mtu configuration of IB ports Or Gerlitz
[not found] ` <alpine.LRH.2.00.1105251507140.16147-VYr5/9ddeaGSIdy2EShu12Xnswh1EIUO@public.gmane.org>
2011-05-25 16:13 ` Roland Dreier
[not found] ` <BANLkTi=bKdVXm+f+HVeg2tBzT4RBJDCN_w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-05-25 21:05 ` Or Gerlitz
[not found] ` <BANLkTinDCbPXi8zS46wcVW_Yn0fxzbSikw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-05-25 21:27 ` Roland Dreier
[not found] ` <BANLkTikrJ_3f+LwN_R=-AcwCde-KdHJhOQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-05-25 21:46 ` Or Gerlitz
[not found] ` <BANLkTinT5OJdP38Xq=PCtx1wgxDhjVfndA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-05-25 22:07 ` Jason Gunthorpe [this message]
2011-05-25 22:10 ` Roland Dreier
[not found] ` <BANLkTi=NkZQX2JFa99qkVpLAchRjNoYOhg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-05-26 6:24 ` Or Gerlitz
[not found] ` <4DDDF212.4080700-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
2011-05-26 15:53 ` Roland Dreier
[not found] ` <BANLkTimrm7bqTT8qAzxdf9tsJuv7+NPO+g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-05-30 22:12 ` Or Gerlitz
2011-05-25 22:19 ` Bob Pearson
2011-05-25 23:14 ` Roland Dreier
[not found] ` <BANLkTikLeWHYLKrX8O=syt-Q+b6LP2PCtw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-05-26 6:18 ` Or Gerlitz
[not found] ` <4DDDF0B1.6090305-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
2011-05-26 14:24 ` Jim Schutt
[not found] ` <17495_1306419903_p4QEMqSb018281_4DDE6291.1090809@sandia.gov>
[not found] ` <17495_1306419903_p4QEMqSb018281_4DDE6291.1090809-4OHPYypu0djtX7QSmKvirg@public.gmane.org>
2011-05-26 14:30 ` Jim Schutt
[not found] ` <4DDE63F9.8060502-4OHPYypu0djtX7QSmKvirg@public.gmane.org>
2011-05-26 15:56 ` Roland Dreier
[not found] ` <BANLkTimGioibPTUYV046ObOPhHntHxx72w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-05-30 22:07 ` Or Gerlitz
[not found] ` <BANLkTinK+YHUyF4ThHQAwFeZ4FNswpY-tw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-05-31 16:11 ` Jim Schutt
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