freebsd-dev/lib/libc/x86/sys/Makefile.inc

# $FreeBSD$

.PATH:	${LIBC_SRCTOP}/x86/sys

SRCS+= \
	__vdso_gettc.c

.if ${MACHINE_CPUARCH} == "amd64" && ${MK_HYPERV} != "no"
CFLAGS+=	-DWANT_HYPERV
.endif
Implement userspace gettimeofday(2) with HPET timecounter. Right now, userspace (fast) gettimeofday(2) on x86 only works for RDTSC. For older machines, like Core2, where RDTSC is not C2/C3 invariant, and which fall to HPET hardware, this means that the call has both the penalty of the syscall and of the uncached hw behind the QPI or PCIe connection to the sought bridge. Nothing can me done against the access latency, but the syscall overhead can be removed. System already provides mappable /dev/hpetX devices, which gives straight access to the HPET registers page. Add yet another algorithm to the x86 'vdso' timehands. Libc is updated to handle both RDTSC and HPET. For HPET, the index of the hpet device to mmap is passed from kernel to userspace, index might be changed and libc invalidates its mapping as needed. Remove cpu_fill_vdso_timehands() KPI, instead require that timecounters which can be used from userspace, to provide tc_fill_vdso_timehands{,32}() methods. Merge i386 and amd64 libc/<arch>/sys/__vdso_gettc.c into one source file in the new libc/x86/sys location. __vdso_gettc() internal interface is changed to move timecounter algorithm detection into the MD code. Measurements show that RDTSC even with the syscall overhead is faster than userspace HPET access. But still, userspace HPET is three-four times faster than syscall HPET on several Core2 and SandyBridge machines. Tested by: Howard Su <howard0su@gmail.com> Sponsored by: The FreeBSD Foundation MFC after: 1 month Differential revision: https://reviews.freebsd.org/D7473 2016-08-17 09:52:09 +00:00			`# $FreeBSD$`

			`.PATH: ${LIBC_SRCTOP}/x86/sys`

			`SRCS+= \`
			`__vdso_gettc.c`
Conditionalize hyperv support in gettimeofday(2) based on MK_HYPERV The effect at runtime is negligible as the hyperv timer isn't available except when hyperv is loaded. This is a prerequisite for conditionalizing the header build/install out of the build MFC after: 3 weeks Reviewed by: sephe Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D9242 2017-01-19 17:03:45 +00:00
Only conditionally add in hyperv support if we're building amd64 This unbreaks the build because the assembly is written for x64. MFC after: 3 weeks X-MFC with: r312418 Pointyhat to: ngie Reported by: Jenkins (i386 job) Sponsored by: Dell EMC Isilon 2017-01-19 18:07:24 +00:00			`.if ${MACHINE_CPUARCH} == "amd64" && ${MK_HYPERV} != "no"`
Conditionalize hyperv support in gettimeofday(2) based on MK_HYPERV The effect at runtime is negligible as the hyperv timer isn't available except when hyperv is loaded. This is a prerequisite for conditionalizing the header build/install out of the build MFC after: 3 weeks Reviewed by: sephe Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D9242 2017-01-19 17:03:45 +00:00			`CFLAGS+= -DWANT_HYPERV`
			`.endif`