On Fri, 25 Oct 2013, Scott Wood wrote: > Has anyone measured how much this slows things down with a typical > userspace?
Not a measurement of the patch in question but an older similar patch on 3.0.51 (8572 running Debian 5.0.3): $ ./test-lwsync cycles per emulated lwsync = 371 cycles per sync = 36 ---------------------------------------------------------- #include <stdio.h> int main (void) { unsigned long atb_start, atb_stop; unsigned long i; asm volatile ("mfspr %0,526" : "=r" (atb_start)); for (i = 0; i < 100; i++) { asm volatile ("lwsync"); } asm volatile ("mfspr %0,526" : "=r" (atb_stop)); printf("cycles per emulated lwsync = %lu\n", (atb_stop - atb_start) / 100); asm volatile ("mfspr %0,526" : "=r" (atb_start)); for (i = 0; i < 100; i++) { asm volatile ("sync"); } asm volatile ("mfspr %0,526" : "=r" (atb_stop)); printf("cycles per sync = %lu\n", (atb_stop - atb_start) / 100); return 0; } ---------------------------------------------------------- _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev