From: LIN Q. <nlv...@na...> - 2007-06-29 14:37:24
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Hi,Dave and all, yes,it is 0.18-0.22A. I only find ../build_arm_nofpu/linux-2.6.20gum/arch/arm/kernel/process.c, which includes function cpu_idle. How can I make use of it? build a executable binary myself? Or is there already any commands could be used to switch the CPU power mode? Besides, there is following problems when I am trying to some setting to wifi: # iwconfig -wlan0 power period 2 iwconfig: can't resolve symbol '__aeabi_d2iz' Also, how can I parse the information from iwconfig to decides on whether the network is busy or idle right now? LIN > > Message: 7 > Date: Fri, 29 Jun 2007 06:55:19 -0700 > From: "Dave Hylands" <dhy...@gm...> > Subject: Re: [Gumstix-users] The kernel already executes some kind of > idle instruction to reduces power usage? > To: "General mailing list for gumstix users." > <gum...@li...> > Message-ID: > <c32...@ma...> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > HI Lin, > > > I just found someone discussed this before in the archive of mailing > > list. Does anyone have some knowledge or prove that the kernel had > > already executes some kind of idle instruction to reduces power usage? > > My gumstix consumes 0.18-0.22mA when doing nothing(wifi off). > > That seems a little low. Maybe you meant 0.18 - 0.22 A which would be > 180 to 220 mA, which is more in line with what I would expect. > > The idle process is defined by the function cpu_idle, which can be > found in arch/arm/process.c > > The default idle routine is called "default_idle" and it calls > arch_idle, which is just a wrapper for cpu_do_idle, which in turn is a > macro for cpu_xscale_do_idle, which does this: > > /* > * cpu_xscale_do_idle() > * > * Cause the processor to idle > * > * For now we do nothing but go to idle mode for every case > * > * XScale supports clock switching, but using idle mode support > * allows external hardware to react to system state changes. > */ > .align 5 > > ENTRY(cpu_xscale_do_idle) > mov r0, #1 > mcr p14, 0, r0, c7, c0, 0 @ Go to IDLE > mov pc, lr > |
From: Dave H. <dhy...@gm...> - 2007-06-29 15:57:40
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Hi Lin, > How can I make use of it? build a executable binary myself? Or is there > already any commands could be used to switch the CPU power mode? You don't need to do anything. It's already being used. -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ |
From: LIN Q. <nlv...@na...> - 2007-07-02 07:35:05
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hi, Dave, Because I was asked to investigate into possible solutions to reduce the power consumption. then how can I prove it(that any lower power CPU mechanism has already been used)? the lowest current I got is 0.16A, doesn't look like enter into sleep or idle mode anytime. LIN On Fri, 2007-06-29 at 08:57 -0700, Dave Hylands wrote: > gumstix_mailinglist |
From: Craig H. <cr...@gu...> - 2007-07-02 17:18:26
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On Jul 2, 2007, at 12:34 AM, LIN QIU wrote: > Because I was asked to investigate into possible solutions to > reduce the > power consumption. > > then how can I prove it(that any lower power CPU mechanism has already > been used)? > > the lowest current I got is 0.16A, doesn't look like enter into > sleep or > idle mode anytime. Boot to kernel login prompt. Watch current. Now log in and execute this shell command: while 1;done Now watch current. Did the current go up? Now hold ctrl-c till you get back to command prompt. Watch current. Did current go down again? C |
From: LIN Q. <nlv...@na...> - 2007-07-02 14:43:11
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Hi, and regarding to comment out the call to arch_idle, do I have to recompile and flush the whole filesystem? or if there is more convenient way? did anyone tried this before? LIN On Mon, 2007-07-02 at 01:58 -0700, Dave Hylands wrote: > > Because I was asked to investigate into possible solutions to reduce the > > power consumption. > > > > then how can I prove it(that any lower power CPU mechanism has already > > been used)? > > Comment out the call to arch_idle and see how the current changes. > > What does the top command show? > > Craig asked you for this, but you haven't showed us the output yet. > |
From: Dave H. <dhy...@gm...> - 2007-07-02 16:47:22
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Hi Lin, > and regarding to comment out the call to arch_idle, do I have to > recompile and flush the whole filesystem? or if there is more convenient > way? You only really need to replace the kernel, but based on your other comments and questions, replacing the whole filesystem is probably the simplest way to achieve this. > did anyone tried this before? You're the first person who's asked for proof. -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ |