[openib-general] Re: IBM utilizing and testing openIB release 1 RCx

[Shirley Ma]

Roland,

>How big of a send queue do you need/want?  I'm having a hard time
>understanding why a big txqueuelen doesn't give you the same effect.

On the sending path we have three queues, they are:
1. txqueuelen refers to  the maximum size of the device's transmit queue
2. TX_RING_SIZE (which equals to QP sendq queue size in IPoIB now)
3. IPoIB QP sendq queue size refers to maximum size of send work queue 
elements to be posted on the device.

We do see three times better performance improvement under some workload 
when increaing QP sendq size (sendq_size=64 vs. sendq_size=1024). 

Thanks
Shirley Ma
IBM Linux Technology Center
15300 SW Koll Parkway
Beaverton, OR 97006-6063
Phone(Fax): (503) 578-7638
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