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From: Leon Romanovsky <leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: Jason Gunthorpe
	<jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
Cc: Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Feras Daoud <ferasda-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>,
	Noa Osherovich <noaos-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Subject: Re: [PATCH rdma-next V1 1/9] IB/ipoib: Add warning message when changing the MTU in UD over the max range
Date: Fri, 13 Jan 2017 22:31:27 +0200	[thread overview]
Message-ID: <20170113203127.GT20392@mtr-leonro.local> (raw)
In-Reply-To: <20170113171234.GA30551-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>

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On Fri, Jan 13, 2017 at 10:12:34AM -0700, Jason Gunthorpe wrote:
> On Fri, Jan 13, 2017 at 05:08:24PM +0200, Leon Romanovsky wrote:
> > On Thu, Jan 12, 2017 at 01:16:22PM -0700, Jason Gunthorpe wrote:
> > > On Thu, Jan 12, 2017 at 09:35:08PM +0200, Leon Romanovsky wrote:
> > >
> > > > > > In datagram mode, the IB UD (Unreliable Datagram) transport is used
> > > > > > so the MTU of the interface is equal to the IB L2 MTU minus the
> > > > > > IPoIB encapsulation header. Any request to change the MTU value
> > > > > > above the maximum range will change the MTU to the max allowed, but
> > > > > > will not show any warning message. An ipoib_warn is issued in such
> > > > > > cases, letting the user know that even though the value is legal,
> > > > > > it can't be currently applied.
> > >
> > > How does RC mode work then?
> >
> > RC mode doesn't have limitation on MTU size and it allows messages
> > larger than IB link-layer MTU.
>
> This is about what happens if the multicast MTU < unicast MTU - which
> is *exactly* the same case on RC and UD.
>
> IPoIB cannot send a 64k multicast MTU on RC either.

Multicast is sent in datagram despite being in connected mode and for
datagram the MTU is limited by IB

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  parent reply	other threads:[~2017-01-13 20:31 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-28 12:47 [PATCH rdma-next V1 0/9] IPoIB fixes for 4.11 Leon Romanovsky
     [not found] ` <20161228124728.26619-1-leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2016-12-28 12:47   ` [PATCH rdma-next V1 1/9] IB/ipoib: Add warning message when changing the MTU in UD over the max range Leon Romanovsky
     [not found]     ` <20161228124728.26619-2-leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2017-01-12 18:46       ` Doug Ledford
     [not found]         ` <1484246776.123135.19.camel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2017-01-12 19:35           ` Leon Romanovsky
     [not found]             ` <20170112193508.GO20392-U/DQcQFIOTAAJjI8aNfphQ@public.gmane.org>
2017-01-12 20:16               ` Jason Gunthorpe
     [not found]                 ` <20170112201622.GA14584-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2017-01-13 15:08                   ` Leon Romanovsky
     [not found]                     ` <20170113150824.GQ20392-U/DQcQFIOTAAJjI8aNfphQ@public.gmane.org>
2017-01-13 17:12                       ` Jason Gunthorpe
     [not found]                         ` <20170113171234.GA30551-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2017-01-13 20:31                           ` Leon Romanovsky [this message]
     [not found]                             ` <20170113203127.GT20392-U/DQcQFIOTAAJjI8aNfphQ@public.gmane.org>
2017-01-13 21:27                               ` Jason Gunthorpe
     [not found]                                 ` <20170113212721.GB1463-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2017-01-15  8:35                                   ` Leon Romanovsky
     [not found]                                     ` <20170115083543.GA20392-U/DQcQFIOTAAJjI8aNfphQ@public.gmane.org>
2017-01-16 20:12                                       ` Jason Gunthorpe
     [not found]                                         ` <20170116201218.GA7890-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2017-01-17 19:31                                           ` Leon Romanovsky
2017-01-19 13:12                                           ` Leon Romanovsky
     [not found]                                             ` <20170119131258.GT32481-U/DQcQFIOTAAJjI8aNfphQ@public.gmane.org>
2017-01-19 17:33                                               ` Jason Gunthorpe
     [not found]                                                 ` <20170119173352.GA8109-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2017-01-22  8:05                                                   ` Leon Romanovsky
2017-01-12 21:58               ` Doug Ledford
     [not found]                 ` <1484258308.123135.41.camel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2017-01-13 15:15                   ` Leon Romanovsky
     [not found]                     ` <20170113151507.GR20392-U/DQcQFIOTAAJjI8aNfphQ@public.gmane.org>
2017-01-17 19:34                       ` Leon Romanovsky
2016-12-28 12:47   ` [PATCH rdma-next V1 2/9] IB/ipoib: Set device connection mode only when needed Leon Romanovsky
     [not found]     ` <20161228124728.26619-3-leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2017-01-12 18:47       ` Doug Ledford
     [not found]         ` <1484246826.123135.20.camel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2017-01-12 19:25           ` Leon Romanovsky
2016-12-28 12:47   ` [PATCH rdma-next V1 3/9] IB/ipoib: Fix deadlock over vlan_mutex Leon Romanovsky
2016-12-28 12:47   ` [PATCH rdma-next V1 4/9] IB/ipoib: Fix deadlock between rmmod and set_mode Leon Romanovsky
2016-12-28 12:47   ` [PATCH rdma-next V1 5/9] IB/ipoib: rtnl_unlock can not come after free_netdev Leon Romanovsky
     [not found]     ` <20161228124728.26619-6-leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2016-12-29 20:55       ` Or Gerlitz
     [not found]         ` <CAJ3xEMg+UuvUqqaFrBXa+S+S2qLg_FowZLrwvhYzaB7JTkn=pQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-01-01  6:39           ` Leon Romanovsky
     [not found]             ` <20170101063945.GP26885-U/DQcQFIOTAAJjI8aNfphQ@public.gmane.org>
2017-01-01  7:19               ` Or Gerlitz
     [not found]                 ` <CAJ3xEMj-6aLraLqH+VBeyqTivSnB0hRo_Hzaiy_LChX8yXDjVg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-01-01  7:45                   ` Erez Shitrit
2016-12-28 12:47   ` [PATCH rdma-next V1 6/9] IB/ipoib: Add detailed error message to dev_queue_xmit call Leon Romanovsky
2016-12-28 12:47   ` [PATCH rdma-next V1 7/9] IB/ipoib: Use debug prints instead of warnings in RNR WC status Leon Romanovsky
     [not found]     ` <20161228124728.26619-8-leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2016-12-28 13:11       ` Yuval Shaia
2016-12-28 12:47   ` [PATCH rdma-next V1 8/9] IB/ipoib: Replace list_del of the neigh->list with list_del_init Leon Romanovsky
     [not found]     ` <20161228124728.26619-9-leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2017-01-02 12:29       ` Yuval Shaia
     [not found]         ` <20170102122917.GB25669-Hxa29pjIrETlQW142y8m19+IiqhCXseY@public.gmane.org>
2017-01-02 18:19           ` Leon Romanovsky
2016-12-28 12:47   ` [PATCH rdma-next V1 9/9] IB/ipoib: Change list_del to list_del_init in the tx object Leon Romanovsky
     [not found]     ` <20161228124728.26619-10-leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2017-01-02 12:21       ` Yuval Shaia
2017-01-12 19:02   ` [PATCH rdma-next V1 0/9] IPoIB fixes for 4.11 Doug Ledford
     [not found]     ` <1484247737.123135.21.camel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2017-01-12 19:24       ` Leon Romanovsky

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