Author: sephe Date: Mon Dec 19 07:40:45 2016 New Revision: 310239 URL: https://svnweb.freebsd.org/changeset/base/310239
Log: hyperv: Implement userspace gettimeofday(2) with Hyper-V reference TSC This 6 times gettimeofday performance, as measured by tools/tools/syscall_timing Reviewed by: kib MFC after: 1 week Sponsored by: Microsoft Differential Revision: https://reviews.freebsd.org/D8789 Modified: head/lib/libc/x86/sys/__vdso_gettc.c head/sys/dev/hyperv/vmbus/amd64/hyperv_machdep.c head/sys/sys/vdso.h head/sys/x86/include/vdso.h Modified: head/lib/libc/x86/sys/__vdso_gettc.c ============================================================================== --- head/lib/libc/x86/sys/__vdso_gettc.c Mon Dec 19 00:28:04 2016 (r310238) +++ head/lib/libc/x86/sys/__vdso_gettc.c Mon Dec 19 07:40:45 2016 (r310239) @@ -45,6 +45,10 @@ __FBSDID("$FreeBSD$"); #include <machine/cpufunc.h> #include <machine/specialreg.h> #include <dev/acpica/acpi_hpet.h> +#ifdef __amd64__ +#include <machine/atomic.h> +#include <dev/hyperv/hyperv.h> +#endif #include "libc_private.h" static void @@ -144,6 +148,67 @@ __vdso_init_hpet(uint32_t u) _close(fd); } +#ifdef __amd64__ + +#define HYPERV_REFTSC_DEVPATH "/dev/" HYPERV_REFTSC_DEVNAME + +/* + * NOTE: + * We use 'NULL' for this variable to indicate that initialization + * is required. And if this variable is 'MAP_FAILED', then Hyper-V + * reference TSC can not be used, e.g. in misconfigured jail. + */ +static struct hyperv_reftsc *hyperv_ref_tsc; + +static void +__vdso_init_hyperv_tsc(void) +{ + int fd; + + fd = _open(HYPERV_REFTSC_DEVPATH, O_RDONLY); + if (fd < 0) { + /* Prevent the caller from re-entering. */ + hyperv_ref_tsc = MAP_FAILED; + return; + } + hyperv_ref_tsc = mmap(NULL, sizeof(*hyperv_ref_tsc), PROT_READ, + MAP_SHARED, fd, 0); + _close(fd); +} + +static int +__vdso_hyperv_tsc(struct hyperv_reftsc *tsc_ref, u_int *tc) +{ + uint64_t disc, ret, tsc, scale; + uint32_t seq; + int64_t ofs; + + while ((seq = atomic_load_acq_int(&tsc_ref->tsc_seq)) != 0) { + scale = tsc_ref->tsc_scale; + ofs = tsc_ref->tsc_ofs; + + lfence_mb(); + tsc = rdtsc(); + + /* ret = ((tsc * scale) >> 64) + ofs */ + __asm__ __volatile__ ("mulq %3" : + "=d" (ret), "=a" (disc) : + "a" (tsc), "r" (scale)); + ret += ofs; + + atomic_thread_fence_acq(); + if (tsc_ref->tsc_seq == seq) { + *tc = ret; + return (0); + } + + /* Sequence changed; re-sync. */ + } + return (ENOSYS); +} + +#endif /* __amd64__ */ + #pragma weak __vdso_gettc int __vdso_gettc(const struct vdso_timehands *th, u_int *tc) @@ -165,6 +230,14 @@ __vdso_gettc(const struct vdso_timehands return (ENOSYS); *tc = *(volatile uint32_t *)(hpet_dev_map + HPET_MAIN_COUNTER); return (0); +#ifdef __amd64__ + case VDSO_TH_ALGO_X86_HVTSC: + if (hyperv_ref_tsc == NULL) + __vdso_init_hyperv_tsc(); + if (hyperv_ref_tsc == MAP_FAILED) + return (ENOSYS); + return (__vdso_hyperv_tsc(hyperv_ref_tsc, tc)); +#endif default: return (ENOSYS); } Modified: head/sys/dev/hyperv/vmbus/amd64/hyperv_machdep.c ============================================================================== --- head/sys/dev/hyperv/vmbus/amd64/hyperv_machdep.c Mon Dec 19 00:28:04 2016 (r310238) +++ head/sys/dev/hyperv/vmbus/amd64/hyperv_machdep.c Mon Dec 19 07:40:45 2016 (r310239) @@ -33,6 +33,7 @@ __FBSDID("$FreeBSD$"); #include <sys/kernel.h> #include <sys/systm.h> #include <sys/timetc.h> +#include <sys/vdso.h> #include <machine/cpufunc.h> #include <machine/cputypes.h> @@ -52,18 +53,20 @@ struct hyperv_reftsc_ctx { struct hyperv_dma tsc_ref_dma; }; +static uint32_t hyperv_tsc_vdso_timehands( + struct vdso_timehands *, + struct timecounter *); + static d_open_t hyperv_tsc_open; static d_mmap_t hyperv_tsc_mmap; static struct timecounter hyperv_tsc_timecounter = { .tc_get_timecount = NULL, /* based on CPU vendor. */ - .tc_poll_pps = NULL, .tc_counter_mask = 0xffffffff, .tc_frequency = HYPERV_TIMER_FREQ, .tc_name = "Hyper-V-TSC", .tc_quality = 3000, - .tc_flags = 0, - .tc_priv = NULL + .tc_fill_vdso_timehands = hyperv_tsc_vdso_timehands, }; static struct cdevsw hyperv_tsc_cdevsw = { @@ -117,6 +120,18 @@ hyperv_tsc_mmap(struct cdev *dev __unuse return (0); } +static uint32_t +hyperv_tsc_vdso_timehands(struct vdso_timehands *vdso_th, + struct timecounter *tc __unused) +{ + + vdso_th->th_algo = VDSO_TH_ALGO_X86_HVTSC; + vdso_th->th_x86_shift = 0; + vdso_th->th_x86_hpet_idx = 0; + bzero(vdso_th->th_res, sizeof(vdso_th->th_res)); + return (1); +} + #define HYPERV_TSC_TIMECOUNT(fence) \ static u_int \ hyperv_tsc_timecount_##fence(struct timecounter *tc) \ Modified: head/sys/sys/vdso.h ============================================================================== --- head/sys/sys/vdso.h Mon Dec 19 00:28:04 2016 (r310238) +++ head/sys/sys/vdso.h Mon Dec 19 07:40:45 2016 (r310239) @@ -54,6 +54,8 @@ struct vdso_timekeep { #define VDSO_TK_VER_CURR VDSO_TK_VER_1 #define VDSO_TH_ALGO_1 0x1 #define VDSO_TH_ALGO_2 0x2 +#define VDSO_TH_ALGO_3 0x3 +#define VDSO_TH_ALGO_4 0x4 #ifndef _KERNEL Modified: head/sys/x86/include/vdso.h ============================================================================== --- head/sys/x86/include/vdso.h Mon Dec 19 00:28:04 2016 (r310238) +++ head/sys/x86/include/vdso.h Mon Dec 19 07:40:45 2016 (r310239) @@ -39,6 +39,7 @@ #define VDSO_TH_ALGO_X86_TSC VDSO_TH_ALGO_1 #define VDSO_TH_ALGO_X86_HPET VDSO_TH_ALGO_2 +#define VDSO_TH_ALGO_X86_HVTSC VDSO_TH_ALGO_3 /* Hyper-V ref. TSC */ #ifdef _KERNEL #ifdef COMPAT_FREEBSD32 _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
