88 lines
1.5 KiB
C
88 lines
1.5 KiB
C
/* getidle.c - by David van Moolenbroek <dcvmoole@cs.vu.nl> */
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/* Usage:
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*
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* double idleperc;
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* getidle();
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* ...
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* idleperc = getidle();
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* if (idleperc >= 0.0)
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* printf("CPU usage: %lg%%\n", 100.0 - idleperc);
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*
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* Notes:
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* - This functionality can only be used by system processes.
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* - The kernel has to be compiled with CONFIG_IDLE_TSC support.
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* - Only one getidle() run is allowed per process at a time.
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*
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*/
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#define _MINIX 1
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#define _SYSTEM 1
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#include <lib.h>
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#include <minix/u64.h>
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#include <minix/sysutil.h>
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static u64_t start, idle;
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static int running = 0;
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static double make_double(u64_t d)
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{
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/* Convert a 64-bit fixed point value into a double.
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* This whole thing should be replaced by something better eventually.
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*/
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double value;
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size_t i;
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value = (double) ex64hi(d);
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for (i = 0; i < sizeof(unsigned long); i += 2)
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value *= 65536.0;
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value += (double) ex64lo(d);
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return value;
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}
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double getidle(void)
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{
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u64_t stop, idle2;
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u64_t idelta, tdelta;
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double ifp, tfp, rfp;
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int r;
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if (!running) {
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if ((r = sys_getidletsc(&idle)) != OK)
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return -1.0;
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running = 1;
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read_tsc_64(&start);
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return 0.0;
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}
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else {
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read_tsc_64(&stop);
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running = 0;
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if ((r = sys_getidletsc(&idle2)) != OK)
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return -1.0;
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idelta = sub64(idle2, idle);
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tdelta = sub64(stop, start);
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if (cmp64(idelta, tdelta) >= 0)
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return 100.0;
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ifp = make_double(idelta);
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tfp = make_double(tdelta);
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rfp = ifp / tfp * 100.0;
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if (rfp < 0.0) rfp = 0.0;
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else if (rfp > 100.0) rfp = 100.0;
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return rfp;
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}
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running = !running;
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}
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