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From: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
To: "Davis, Arlin R" <arlin.r.davis-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Cc: "Hefty,
	Sean" <sean.hefty-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	linux-rdma <linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	"ofw-ZwoEplunGu1OwGhvXhtEPSCwEArCW2h5@public.gmane.org"
	<ofw-ZwoEplunGu1OwGhvXhtEPSCwEArCW2h5@public.gmane.org>
Subject: Re: [PATCH] DAPL v2.0: common: increase default IB ack timer from 16 to 20
Date: Wed, 2 Nov 2011 20:28:22 -0600	[thread overview]
Message-ID: <20111103022822.GA6674@obsidianresearch.com> (raw)
In-Reply-To: <54347E5A035A054EAE9D05927FB467F916E931E8-P5GAC/sN6hmkrb+BlOpmy7fspsVTdybXVpNB7YpNyf8@public.gmane.org>

On Wed, Nov 02, 2011 at 11:31:38PM +0000, Davis, Arlin R wrote:
> > > Yes, a user can modify path lifetime via rdma_create_ep() but there
> > > is no way for the user to know how much that will be manipulated and
> > > increased in the IB CM driver.
> > 
> > Sure there is.  It's an open source driver.  :)
> > 
> > The ib_cm calculates the "correct" timeout based on the packet lifetime
> > provided by the SA and the CA ack timeout.  If user modifications to
> > this value are necessary, then there is a bug in either the SA or HCA
> > driver.
> 
> or there could be congestion on the fabric that the SA or HCA driver
> is unaware of.

That is what packet life time is supposed to model, and the policy
knob for it belongs in the SA, not every app..

Jason
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      parent reply	other threads:[~2011-11-03  2:28 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-11-02 21:35 [PATCH] DAPL v2.0: common: increase default IB ack timer from 16 to 20 Davis, Arlin R
     [not found] ` <54347E5A035A054EAE9D05927FB467F916E93128-P5GAC/sN6hmkrb+BlOpmy7fspsVTdybXVpNB7YpNyf8@public.gmane.org>
2011-11-02 22:40   ` Hefty, Sean
     [not found]     ` <1828884A29C6694DAF28B7E6B8A8237316E8CBCB-P5GAC/sN6hmkrb+BlOpmy7fspsVTdybXVpNB7YpNyf8@public.gmane.org>
2011-11-02 23:09       ` Davis, Arlin R
     [not found]         ` <54347E5A035A054EAE9D05927FB467F916E931C5-P5GAC/sN6hmkrb+BlOpmy7fspsVTdybXVpNB7YpNyf8@public.gmane.org>
2011-11-02 23:19           ` Hefty, Sean
2011-11-02 23:31             ` Davis, Arlin R
     [not found]               ` <54347E5A035A054EAE9D05927FB467F916E931E8-P5GAC/sN6hmkrb+BlOpmy7fspsVTdybXVpNB7YpNyf8@public.gmane.org>
2011-11-03  2:28                 ` Jason Gunthorpe [this message]

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