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runtime: use sched_getaffinity for runtime.NumCPU() on Linux
Fixes #3921. R=iant CC=golang-dev https://golang.org/cl/6448132
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@ -423,3 +423,11 @@ TEXT runtime·osyield(SB),7,$0
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MOVL $158, AX
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CALL *runtime·_vdso(SB)
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RET
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TEXT runtime·sched_getaffinity(SB),7,$0
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MOVL $242, AX // syscall - sched_getaffinity
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MOVL 4(SP), BX
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MOVL 8(SP), CX
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MOVL 12(SP), DX
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CALL *runtime·_vdso(SB)
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RET
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@ -310,3 +310,11 @@ TEXT runtime·osyield(SB),7,$0
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MOVL $24, AX
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SYSCALL
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RET
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TEXT runtime·sched_getaffinity(SB),7,$0
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MOVQ 8(SP), DI
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MOVL 16(SP), SI
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MOVQ 24(SP), DX
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MOVL $204, AX // syscall entry
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SYSCALL
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RET
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@ -34,6 +34,7 @@
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#define SYS_sched_yield (SYS_BASE + 158)
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#define SYS_select (SYS_BASE + 142) // newselect
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#define SYS_ugetrlimit (SYS_BASE + 191)
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#define SYS_sched_getaffinity (SYS_BASE + 242)
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#define ARM_BASE (SYS_BASE + 0x0f0000)
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#define SYS_ARM_cacheflush (ARM_BASE + 2)
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@ -393,3 +394,11 @@ TEXT runtime·osyield(SB),7,$0
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MOVW $SYS_sched_yield, R7
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SWI $0
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RET
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TEXT runtime·sched_getaffinity(SB),7,$0
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MOVW 0(FP), R0
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MOVW 4(FP), R1
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MOVW 8(FP), R2
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MOVW $SYS_sched_getaffinity, R7
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SWI $0
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RET
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@ -80,33 +80,23 @@ runtime·futexwakeup(uint32 *addr, uint32 cnt)
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*(int32*)0x1006 = 0x1006;
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}
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extern runtime·sched_getaffinity(uintptr pid, uintptr len, uintptr *buf);
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static int32
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getproccount(void)
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{
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int32 fd, rd, cnt, cpustrlen;
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byte *cpustr, *pos, *bufpos;
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byte buf[256];
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uintptr buf[16], t;
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int32 r, cnt, i;
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fd = runtime·open((byte*)"/proc/stat", O_RDONLY|O_CLOEXEC, 0);
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if(fd == -1)
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return 1;
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cnt = 0;
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bufpos = buf;
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cpustr = (byte*)"\ncpu";
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cpustrlen = runtime·findnull(cpustr);
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for(;;) {
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rd = runtime·read(fd, bufpos, sizeof(buf)-cpustrlen);
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if(rd == -1)
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break;
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bufpos[rd] = 0;
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for(pos=buf; pos=runtime·strstr(pos, cpustr); cnt++, pos++) {
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}
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if(rd < cpustrlen)
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break;
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runtime·memmove(buf, bufpos+rd-cpustrlen+1, cpustrlen-1);
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bufpos = buf+cpustrlen-1;
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r = runtime·sched_getaffinity(0, sizeof(buf), buf);
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if(r > 0)
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for(i = 0; i < r/sizeof(buf[0]); i++) {
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t = buf[i];
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t = t - ((t >> 1) & 0x5555555555555555ULL);
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t = (t & 0x3333333333333333ULL) + ((t >> 2) & 0x3333333333333333ULL);
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cnt += (int32)((((t + (t >> 4)) & 0xF0F0F0F0F0F0F0FULL) * 0x101010101010101ULL) >> 56);
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}
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runtime·close(fd);
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return cnt ? cnt : 1;
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}
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