Re: [PATCH v4 14/19] IB/core: Add IB_DEVICE_OPA_MAD_SUPPORT device cap flag

["ira.weiny" <ira.weiny-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

On Wed, Mar 25, 2015 at 11:30:32AM +0100, Michael Wang wrote:
> Hi, Sean
> 
> On 03/24/2015 01:49 PM, Michael Wang wrote:
> >On 03/23/2015 05:31 PM, Hefty, Sean wrote:
> >>>[snip]
> >>To restate my suggesting, I was thinking of defining something like 
> >>this:
> >>
> >>enum {
> >>    IB_MGMT_PROTO_SM = (1 << 0),   /* supports IB SMPs */
> >>    IB_MGMT_PROTO_SA = (1 << 1),   /* supports IB SA MADs */
> >>    IB_MGMT_PROTO_GS = (1 << 2),   /* supports IB GSI MADs (e.g. PM, 
> >>...) */
> >>    IB_MGMT_PROTO_CM = (1 << 3),   /* IB CM called out separately */
> >>    IB_MGMT_PROTO_IW_CM = (1 << 4),/* iWarp CM */
> >>    /* OPA can define new values here */
> >>};
> >>
> >>struct ib_port_attr {
> >>    ...
> >>    u32    mgmt_proto;  /* bitmask of supported protocols */
> >>};
> >
> >Thanks for the restate, Sean :) seems like your proposal is also to 
> >ask vendor
> >setup 'mgmt_proto' during ib_query_port(), correct?
> 
> I think we got one problem here, if we rely on ib_query_port() to setup 
> mgmt flags
> each time, the performance may suffered, since some implementation of
> query_port() is really expensive, like hardware communication (mlx4/5) and
> mutex protection (usnic)...

This is why my OPA patch series included a cache of the device attributes.

https://www.mail-archive.com/linux-rdma%40vger.kernel.org/msg22827.html

This was suggested by Or and incorporated rather than having the MAD stack
issue ib_query_device.  The same could be done for port attributes.

That said I would like to see the next version of your patch series.  We have
had a lot of churn on that thread and I think you have a lot of things you were
going to incorporate.  :-D

Thanks!
Ira

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