Messages in this thread | | | Date | Fri, 27 Aug 2010 11:33:02 -0700 | From | Bryan Huntsman <> | Subject | Re: [PATCH] pm_qos: Add system bus performance parameter |
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Kevin Hilman wrote: > Saravana Kannan <skannan@codeaurora.org> writes: > >> Some drivers/devices might need some minimum system bus performance to >> provide acceptable service. Provide a PM QoS parameter to send these requests >> to. >> >> The new parameter is named "system bus performance" since it is generic enough >> for the unit of the request to be frequency, bandwidth or something else that >> might be appropriate. It's up to each implementation of the QoS provider to >> define what the unit of the request would be. >> >> Signed-off-by: Saravana Kannan <skannan@codeaurora.org> > > With this current design, only one system-wide bus would be managed. > What if a platform has more than one independently scalable bus? > > I think the only scalable way to handle this kind of thing is to have > per-device QoS constraints that can then be combined/aggregated by parent > devices/busses. > > At LPC this year, I've proposed per-device QoS constraints[1] as a topic > for the PM mini-conf. I hope some folks from the MSM camp can be there > for these discussions. > > Kevin > > [1] http://www.linuxplumbersconf.org/2010/ocw/proposals/819
Yeah, I'm planning on rounding up some MSM folks for LPC this year. Power is a big concern for us so it would be good to join the discussion. Initially, I was very keen on the per-device QoS contraints but I've since cooled on it. For our HW, there's not a generic unit that can convey enough data for us to act on. At least not w/o lookup tables, etc., at which point the unit loses it's value and becomes a generic handle. I'm looking forward to a good group discussion on this topic. Thanks.
- Bryan
-- Sent by an employee of the Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
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