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

[Tang, Changqing]

Thanks for your good point.  --CQ 

> -----Original Message-----
> From: Roland Dreier [mailto:rdreier at cisco.com] 
> Sent: Thursday, February 15, 2007 11:59 AM
> To: Tang, Changqing
> Cc: Michael S. Tsirkin; openib-general at openib.org
> Subject: Re: How heavy to resize a CQ ?
> 
>  > 	 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 ?
> 
> I would say that resizing a CQ is not lightweight -- I've 
> never benchmarked it but it's probably comparable to creating 
> a CQ or something like that.  There is no requirement to 
> drain the CQ or anything like that before resizing it -- you 
> can resize it any time, even if it is currently getting 
> completions or being polled.
> 
>  - R.
>