[openib-general] How heavy to resize a CQ ?

[Tang, Changqing]

Roland or other driver developers:

	 In dynamic process application, we don't know how many
connections a process will make when we create the CQ, so we don't know
the CQ size, what we do is to increase the CQ size when a new connection
is made, and decrease the CQ size when a connection is destroyed. My
question is, is ibv_resize_cq() a lightweight function call ?  Do we
have to drain the CQ before we resize the CQ ?

	Thanks

--CQ


> -----Original Message-----
> From: Roland Dreier [mailto:rdreier at cisco.com] 
> Sent: Wednesday, February 07, 2007 5:42 PM
> To: Tang, Changqing
> Cc: Michael S. Tsirkin; openib-general at openib.org
> Subject: Re: Immediate data question
> 
>     Changqing> What I mean is that, is there any performance penalty
>     Changqing> for receiver's overall performance if RNR happens
>     Changqing> continuously on one of the QP ?
> 
> Not for the receiver, but the sender will be severely slowed 
> down by having to wait for the RNR timeouts.
>