Messages in this thread | | | Date | Thu, 8 Nov 2007 12:03:52 -0800 | From | Mark Gross <> | Subject | Re: 2.6.23-mm1 breaks C-state support on Intel T7200 x86_64 |
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On Thu, Nov 08, 2007 at 10:02:12AM -0800, Andrew Morton wrote: > > On Thu, 08 Nov 2007 12:19:44 -0500 Valdis.Kletnieks@vt.edu wrote: > > (Sorry for not reporting this sooner - I haven't been running off battery > > much in the last 3 weeks, so I didn't notice it till now...) > > > > Dell Latitude D820 laptop, T7200 Core2 Duo CPU, x86_64 kernel. > > > > As reported by 'powertop' on a basically idle machine: > > > > 2.6.23-mm1: > > > > Cn Avg residency P-states (frequencies) > > C0 (cpu running) (100.0%) 2.00 Ghz 0.8% > > C1 0.0ms ( 0.0%) 1.67 Ghz 0.0% > > C2 0.0ms ( 0.0%) 1333 Mhz 0.0% > > C3 0.0ms ( 0.0%) 1000 Mhz 99.2% > > > > 2.6.23-rc8-mm2: > > > > Cn Avg residency P-states (frequencies) > > C0 (cpu running) ( 0.3%) 2.00 Ghz 0.0% > > C1 0.0ms ( 0.0%) 1.67 Ghz 0.0% > > C2 0.0ms ( 0.0%) 1333 Mhz 0.0% > > C3 31.5ms (99.7%) 1000 Mhz 100.0% > > > > In addition, the ACPI power estimate reported about 25 watts for 23-mm1, > > but only 21 watts for -rc8-mm2, a significant regression. > > > > I bisected this down to this set of patches: > > > > pm-qos-infrastructure-and-interface.patch > > pm-qos-infrastructure-and-interface-fix.patch > > pm-qos-infrastructure-and-interface-vs-git-acpi.patch > > pm-qos-infrastructure-and-interface-vs-git-acpi-2.patch > > latencyc-use-qos-infrastructure.patch > > > > The patch says: > > > > To register the default pm_qos target for the specific parameter, the > > process must open one of /dev/[cpu_dma_latency, network_latency, > > network_throughput] > > > > As long as the device node is held open that process has a registered > > requirement on the parameter. The name of the requirement is > > "process_<PID>" derived from the current->pid from within the open system > > call. > > > > I shouldn't have to have a process open a /dev/file, write a number, and then > > stay around forever so the file doesn't close in order to get the same behavior > > I was getting by default before. What needs to happen to get this to not > > be a behavior regression/change? > > > > That's a great report, thanks. Over to you, Mark ;) > > btw, I also have a note here that these patches caused Rafael to see an > smp_call_function() inside local_irq_save(). Did that get fixed?
Ah, I see the problem. I think I posted a fix to this. The problem is that what's in the mm1 tree has a parameter PM_QOS_IDLE that needed to be PM_QOS_CPU_DMA_LATENCY.
I'm not sure what's in the current MM tree at this point so I can't say its been fixed. Is there an easy way from me to see what's currently in MM?
FWIW I think I fixed this when I fixed up Rafael's issue. Would you like me to send out a re-fresh patch against 2.6.23-mm1?
--mgross
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