The branch stable/12 has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=4ab4f06952eaee865326e0da7512f49c580d8a32
commit 4ab4f06952eaee865326e0da7512f49c580d8a32 Author: Konstantin Belousov <[email protected]> AuthorDate: 2021-01-05 21:00:14 +0000 Commit: Konstantin Belousov <[email protected]> CommitDate: 2021-02-09 08:36:08 +0000 tsc: add RDTSCP or faster variants of get_timecount() Tested by: pho (cherry picked from commit 9e680e4005b77e3028d28377ee3722a5260f4422) (cherry picked from commit a013e285dfd6b89b1908ca13febb0fdb0a7f3b1f) (cherry picked from commit 9f47eeffa3cfdcb512e2011fb00fc23c7c1a7d75) --- sys/x86/x86/tsc.c | 32 +++++++++++++++++++++++++++++++- 1 file changed, 31 insertions(+), 1 deletion(-) diff --git a/sys/x86/x86/tsc.c b/sys/x86/x86/tsc.c index cb1ba0758db9..f14e0707651c 100644 --- a/sys/x86/x86/tsc.c +++ b/sys/x86/x86/tsc.c @@ -96,6 +96,8 @@ static u_int tsc_get_timecount_lfence(struct timecounter *tc); static u_int tsc_get_timecount_low_lfence(struct timecounter *tc); static u_int tsc_get_timecount_mfence(struct timecounter *tc); static u_int tsc_get_timecount_low_mfence(struct timecounter *tc); +static u_int tscp_get_timecount(struct timecounter *tc); +static u_int tscp_get_timecount_low(struct timecounter *tc); static void tsc_levels_changed(void *arg, int unit); static uint32_t x86_tsc_vdso_timehands(struct vdso_timehands *vdso_th, struct timecounter *tc); @@ -632,7 +634,18 @@ init_TSC_tc(void) init: for (shift = 0; shift <= 31 && (tsc_freq >> shift) > max_freq; shift++) ; - if ((cpu_feature & CPUID_SSE2) != 0 && mp_ncpus > 1) { + + /* + * Timecounter implementation selection, top to bottom: + * - If RDTSCP is available, use RDTSCP. + * - If fence instructions are provided (SSE2), use LFENCE;RDTSC + * on Intel, and MFENCE;RDTSC on AMD. + * - For really old CPUs, just use RDTSC. + */ + if ((amd_feature & AMDID_RDTSCP) != 0) { + tsc_timecounter.tc_get_timecount = shift > 0 ? + tscp_get_timecount_low : tscp_get_timecount; + } else if ((cpu_feature & CPUID_SSE2) != 0 && mp_ncpus > 1) { if (cpu_vendor_id == CPU_VENDOR_AMD || cpu_vendor_id == CPU_VENDOR_HYGON) { tsc_timecounter.tc_get_timecount = shift > 0 ? @@ -785,6 +798,13 @@ tsc_get_timecount(struct timecounter *tc __unused) return (rdtsc32()); } +static u_int +tscp_get_timecount(struct timecounter *tc __unused) +{ + + return (rdtscp32()); +} + static inline u_int tsc_get_timecount_low(struct timecounter *tc) { @@ -795,6 +815,16 @@ tsc_get_timecount_low(struct timecounter *tc) return (rv); } +static u_int +tscp_get_timecount_low(struct timecounter *tc) +{ + uint32_t rv; + + __asm __volatile("rdtscp; movl %1, %%ecx; shrd %%cl, %%edx, %0" + : "=&a" (rv) : "m" (tc->tc_priv) : "ecx", "edx"); + return (rv); +} + static u_int tsc_get_timecount_lfence(struct timecounter *tc __unused) { _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/dev-commits-src-all To unsubscribe, send any mail to "[email protected]"
