Hi Roland, Could you tell me what's the difference between "wmb()" and "mmiowb()". I notice that ofa-1.3 has added "mmiowb()" at the end of mthca_cmd_post, since "wmb()" is already called at the end of cmd_post, is "mmiowb()" really necessary?
Thanks! Yicheng Roland Dreier <[EMAIL PROTECTED]> 01/02/2008 12:13 PM To Jack Morgenstein <[EMAIL PROTECTED]> cc [email protected], Yicheng Jia <[EMAIL PROTECTED]> Subject Re: [ofa-general] synchronize commands issued to MTHCA > Roland, do you think that the memcpy_toio() call might mess things up? I wouldn't think so, although I don't have full details of how your hardware behaves to know for sure. I assume your PCI bus/memory controller is already smart enough to deal with HCR writes being interleaved with writes to a doorbell page from userspace, so it seems that writes to locally attached memory should be OK too, as long as the HCR writes are word-sized in the right order etc. > Maybe we need "wmb()" or "mmiowb()" here as well? I don't see any reason, although I often miss things. It seems that the only thing that cares about the writes of the address info being done would be posting a send WQE that uses it, and that should already have sufficient ordering. What would we be ordering things against? - R. _____________________________________________________________________________ Scanned by IBM Email Security Management Services powered by MessageLabs. For more information please visit http://www.ers.ibm.com _____________________________________________________________________________
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