aboutsummaryrefslogtreecommitdiffstats
path: root/lib/libc/x86/sys/__vdso_gettc.c
Commit message (Collapse)AuthorAgeFilesLines
* Remove resolver_qual from DEFINE_IFUNC/DEFINE_UIFUNC macros.Konstantin Belousov2019-05-161-1/+1
| | | | | | | | | | | | | In all practical situations, the resolver visibility is static. Requested by: markj Sponsored by: The FreeBSD Foundation MFC after: 1 week Approved by: so (emaste) Differential revision: https://reviews.freebsd.org/D20281 Notes: svn path=/head/; revision=347895
* x86 __vdso_gettc(): use machine/cpufunc.h function for CPUID.Konstantin Belousov2019-02-141-27/+2
| | | | | | | | | Based on the discussion with: jkim Sponsored by: The FreeBSD Foundation MFC after: 1 week Notes: svn path=/head/; revision=344119
* Add comment noting that the strange spelling of GenuineIntel is for reason.Konstantin Belousov2019-02-071-0/+1
| | | | | | | | | Requested by: rpokala Sponsored by: The FreeBSD Foundation MFC after: 1 week Notes: svn path=/head/; revision=343859
* Use ifunc to select the barrier instruction for RDTSC.Konstantin Belousov2019-02-071-58/+19
| | | | | | | | | | | | | | | | This optimizes out runtime switch and removes yet another cpuid from libc. Note that this is the first use of ifunc in i386 libc, so ifunc-capable toolchain is required for building runnable userspace on i386, same as on amd64. Discussed with: emaste Sponsored by: The FreeBSD Foundation MFC after: 1 week Notes: svn path=/head/; revision=343855
* Fix a regression in r321608.Konstantin Belousov2017-08-131-2/+2
| | | | | | | | | | | | On i386 with CPUID but without SSE2, set lfence_works to LMB_NONE instead of looping. Reported and tested by: Andre Albsmeier <andre@fbsd.e4m.org> Sponsored by: The FreeBSD Foundation MFC after: 3 days Notes: svn path=/head/; revision=322456
* Simplify flow control.Konstantin Belousov2017-07-281-12/+11
| | | | | | | | | | | Also add explicit comment why libc cannot simply rely on open(2) failure in capability mode. Sponsored by: The FreeBSD Foundation MFC after: 1 week Notes: svn path=/head/; revision=321652
* Use MFENCE to serialize RDTSC on non-Intel CPUs.Konstantin Belousov2017-07-271-38/+89
| | | | | | | | | | | | Kernel already used the stronger barrier instruction for AMDs, correct the userspace fast gettimeofday() implementation as well. Sponsored by: The FreeBSD Foundation MFC after: 2 weeks Differential revision: https://reviews.freebsd.org/D11728 Notes: svn path=/head/; revision=321608
* Fix indent.Konstantin Belousov2017-07-251-1/+1
| | | | | | | | Sponsored by: The FreeBSD Foundation MFC after: 3 days Notes: svn path=/head/; revision=321461
* Remove unneeded variable initialization from r314319.Mariusz Zaborski2017-02-261-2/+0
| | | | | | | Pointed out by: kib Notes: svn path=/head/; revision=314320
* Don't try to open devices in the gettc() function which will alwaysMariusz Zaborski2017-02-261-11/+28
| | | | | | | | | | fail in the Capability mode. Instead silently fallback to the syscall method, which is done for example in the gettimeofday(2) function. Reviewed by: kib Notes: svn path=/head/; revision=314319
* Conditionalize hyperv support in gettimeofday(2) based on MK_HYPERVEnji Cooper2017-01-191-4/+4
| | | | | | | | | | | | | | | | 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 Notes: svn path=/head/; revision=312418
* __vdso_gettc(): be extra careful with /dev/hpet mappings, never unmapKonstantin Belousov2017-01-041-19/+35
| | | | | | | | | | | | | | | | | | | | | the mapping which might be accessed by other threads. If a pointer to the /dev/hpet register page mapping was stored into the hpet_dev_map, other threads might access the page at any time. Never unmap it, instead, keep track of mappings for all hpet units in smal array. Store pointer to the newly mapped registers page using CAS, to detect parallel mappings. It appeared relatively easy to demonstrate the problem by arranging two threads which perform gettimeofday(2) concurently, first time in the process address space, when HPET is used for timecounter. PR: 215715 Sponsored by: The FreeBSD Foundation MFC after: 1 week Notes: svn path=/head/; revision=311287
* hyperv: Implement userspace gettimeofday(2) with Hyper-V reference TSCSepherosa Ziehau2016-12-191-0/+73
| | | | | | | | | | | | | 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 Notes: svn path=/head/; revision=310239
* Implement userspace gettimeofday(2) with HPET timecounter.Konstantin Belousov2016-08-171-0/+179
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 Notes: svn path=/head/; revision=304285