Messages in this thread | | | Date | Thu, 11 Oct 2007 08:08:04 -0700 | From | Mark Gross <> | Subject | Re: pm qos infrastructure and interface |
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On Wed, Oct 10, 2007 at 10:17:04PM -0700, Andrew Morton wrote: > On Thu, 4 Oct 2007 14:51:39 -0700 Mark Gross <mgross@linux.intel.com> wrote: > > > The following patch is a generalization of the latency.c implementation > > done by Arjan last year. It provides infrastructure for more than one > > parameter, and exposes a user mode interface for processes to register > > pm_qos expectations of processes. > > > > > > This interface provides a kernel and user mode interface for registering > > performance expectations by drivers, subsystems and user space > > applications on one of the parameters. > > > > Currently we have {cpu_dma_latency, network_latency, network_throughput} > > as the initial set of pm_qos parameters. > > > > The infrastructure exposes multiple misc device nodes one per > > implemented parameter. The set of parameters implement is defined by > > pm_qos_power_init() and pm_qos_params.h. This is done because having > > the available parameters being runtime configurable or changeable from a > > driver was seen as too easy to abuse. > > I'm a bit surprised that this change appears to have no configurability. > If one has set CONFIG_PM=n (for example), shouldn't it all go away?
We considered that as an option but as latency.c didn't offer it I didn't either.
I could see the user mode interface portion of the implementation be made as a compile time option but the kernel infrastructure will continue to be needed by at least cpu-idel, pcm_native.c and ipw2100.
You know it could make sense to have the user mode interface part of the patch as configurable or a build time dependent of sysfs and misc device support for the linux-tiny guys. Is it practical to make a linux-tiny without the sysfs infrastructure needed to make a misc device? I'll ask on the linux-tiny list.
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