1994/0809/pc/clock.c (diff list | history)

1994/0806/sys/src/9/pc/clock.c:27,33 – 1994/0809/sys/src/9/pc/clock.c:27,34 (short | long | prev | next)
use cpufreq and cpumhz. preempt user processes even in kernel. (BUG fix?) start with longer loops for 586+ (hw BUG fix?) rsc Fri Mar 4 12:44:25 2005
1992/0923		Freq= 1193182, /* Real clock frequency */
1991/0705		};
1994/0716		static int cpufreq = 66;
1994/0809		static int cpufreq = 66000000; static int cpumhz = 66;
1994/0716		static int cputype = 486; static int loopconst = 100;
1992/0923
1994/0806/sys/src/9/pc/clock.c:59,72 – 1994/0809/sys/src/9/pc/clock.c:60,75
1993/1124		nrun = (nrdy+nrun)*1000; MACHP(0)->load = (MACHP(0)->load*19+nrun)/20;
1994/0507		if(up && (ur->cs&0xffff) == UESEL && up->state == Running){
1994/0809		if(up && up->state == Running){
1994/0507		if(anyready()) sched(); /* user profiling clock */
1994/0512		islow = 1;
1994/0507		spllo(); /* in case we fault */ (*(ulong*)(USTKTOP-BY2WD)) += TK2MS(1);
1994/0809		if((ur->cs&0xffff) == UESEL){ islow = 1; spllo(); /* in case we fault */ (*(ulong*)(USTKTOP-BY2WD)) += TK2MS(1); }
1994/0507		}
1993/1124
1994/0512		/*
1994/0806/sys/src/9/pc/clock.c:96,102 – 1994/0809/sys/src/9/pc/clock.c:99,105
1994/0302		void printcpufreq(void) {
1994/0719		print("CPU is a %ud MHz %d\n", cpufreq, cputype);
1994/0809		print("CPU is a %ud MHz (%ud Hz) %d\n", cpumhz, cpufreq, cputype);
1994/0302		}
1991/0704		void
1994/0806/sys/src/9/pc/clock.c:105,110 – 1994/0809/sys/src/9/pc/clock.c:108,128
1992/0923		ulong x, y; /* change in counter */
1994/0716		ulong cycles, loops;
1992/0922
1994/0809		switch(cputype = x86()){ case 386: loops = 10000; cycles = 32; break; case 486: loops = 10000; cycles = 22; break; default: loops = 30000; cycles = 23; break; }
1991/0709		/* * set vector for clock interrupts */
1994/0806/sys/src/9/pc/clock.c:117,122 – 1994/0809/sys/src/9/pc/clock.c:135,141
1991/0709		outb(T0cntr, (Freq/HZ)); /* low byte */ outb(T0cntr, (Freq/HZ)>>8); /* high byte */
1992/0922
1994/0809
1992/0922		/*
1994/0716		* measure time for the loop *
1994/0806/sys/src/9/pc/clock.c:129,135 – 1994/0809/sys/src/9/pc/clock.c:148,153
1994/0716		* prefetch buffer. *
1992/0922		*/
1994/0716		loops = 10000;
1992/0922		outb(Tmode, Latch0);
1992/0923		x = inb(T0cntr); x |= inb(T0cntr)<<8;
1994/0806/sys/src/9/pc/clock.c:141,147 – 1994/0809/sys/src/9/pc/clock.c:159,165
1992/0923		/*
1994/0716		* counter goes at twice the frequency, once per transition, * i.e., twice per the square wave
1994/0809		* i.e., twice per square wave
1992/0923		*/
1994/0716		x >>= 1;
1994/0806/sys/src/9/pc/clock.c:148,167 – 1994/0809/sys/src/9/pc/clock.c:166,176
1994/0716		/* * figure out clock frequency and a loop multiplier for delay(). */ switch(cputype = x86()){ case 386:
1994/0719		cycles = 32;
1994/0716		break; case 486:
1994/0717		cycles = 22;
1994/0716		break; default:
1994/0806		cycles = 24;
1994/0716		break; }
1994/0717		cpufreq = loops*((cycles*Freq)/x);
1994/0716		loopconst = (cpufreq/1000)/cycles; /* AAM+LOOP's for 1 ms */
1994/0719		/* convert to MHz */ cpufreq = cpufreq/1000000;
1994/0809		/* * add in possible .1% error and convert to MHz */ cpumhz = (cpufreq + cpufreq/1000)/1000000;
1991/0808		}