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CPU power consumption vs performance tuning is no longer limited to CPU frequency switching anymore: deep sleep states, traditional dynamic frequency scaling and hidden turbo/boost frequencies are tied close together and depend on each other. The first two exist on different architectures like PPC, Itanium and ARM, the latter (so far) only on X86. On X86 the APU (CPU+GPU) will only run most efficiently if CPU and GPU has proper power management in place. Users and Developers want to have *one* tool to get an overview what their system supports and to monitor and debug CPU power management in detail. The tool should compile and work on as many architectures as possible. Once this tool stabilizes a bit, it is intended to replace the Intel-specific tools in tools/power/x86 Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
97 lines
1.8 KiB
C
97 lines
1.8 KiB
C
/*
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* (C) 2004 Bruno Ducrot <ducrot@poupinou.org>
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*
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* Licensed under the terms of the GNU GPL License version 2.
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*
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* Based on code found in
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* linux/arch/i386/kernel/cpu/cpufreq/powernow-k8.c
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* and originally developed by Paul Devriendt
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include <unistd.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#define MCPU 32
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#define MSR_FIDVID_STATUS 0xc0010042
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#define MSR_S_HI_CURRENT_VID 0x0000001f
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#define MSR_S_LO_CURRENT_FID 0x0000003f
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static int get_fidvid(uint32_t cpu, uint32_t *fid, uint32_t *vid)
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{
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int err = 1;
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uint64_t msr = 0;
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int fd;
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char file[20];
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if (cpu > MCPU)
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goto out;
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sprintf(file, "/dev/cpu/%d/msr", cpu);
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fd = open(file, O_RDONLY);
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if (fd < 0)
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goto out;
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lseek(fd, MSR_FIDVID_STATUS, SEEK_CUR);
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if (read(fd, &msr, 8) != 8)
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goto err1;
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*fid = ((uint32_t )(msr & 0xffffffffull)) & MSR_S_LO_CURRENT_FID;
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*vid = ((uint32_t )(msr>>32 & 0xffffffffull)) & MSR_S_HI_CURRENT_VID;
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err = 0;
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err1:
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close(fd);
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out:
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return err;
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}
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/* Return a frequency in MHz, given an input fid */
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static uint32_t find_freq_from_fid(uint32_t fid)
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{
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return 800 + (fid * 100);
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}
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/* Return a voltage in miliVolts, given an input vid */
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static uint32_t find_millivolts_from_vid(uint32_t vid)
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{
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return 1550-vid*25;
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}
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int main (int argc, char *argv[])
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{
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int err;
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int cpu;
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uint32_t fid, vid;
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if (argc < 2)
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cpu = 0;
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else
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cpu = strtoul(argv[1], NULL, 0);
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err = get_fidvid(cpu, &fid, &vid);
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if (err) {
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printf("can't get fid, vid from MSR\n");
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printf("Possible trouble: you don't run a powernow-k8 capable cpu\n");
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printf("or you are not root, or the msr driver is not present\n");
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exit(1);
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}
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printf("cpu %d currently at %d MHz and %d mV\n",
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cpu,
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find_freq_from_fid(fid),
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find_millivolts_from_vid(vid));
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return 0;
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}
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