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Groups > linux.kernel > #1257234
| From | David Daney <ddaney.cavm@gmail.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() |
| Date | 2015-10-27 22:10 +0100 |
| Message-ID | <qojFj-1MD-65@gated-at.bofh.it> (permalink) |
| References | <qlXpx-6nw-37@gated-at.bofh.it> <qmzEu-3yN-13@gated-at.bofh.it> <qodJw-6ns-17@gated-at.bofh.it> <qojlT-1pk-5@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On 10/27/2015 01:46 PM, Leonid Yegoshin wrote: [...] > > And finally. clock scaling - what we would do if there are two CPUs with > different clock ratios in system? It seems like common kernel timing > subsystem can handle that. > The code that executes in userspace must have access to a consistent clock source. If you are running on a SMP system that doesn't have synchronized CP0.Count registers, then your gettimeofday() cannot use CP0.Count (RDHWR $2). As far as I know, CP0.Count is the only available counter visible to userspace, so you would have to disable the accelerated versions of gettimeofday() where you cannot assert that the counters are always synchronized. David Daney -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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[PATCH v3 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() Markos Chandras <markos.chandras@imgtec.com> - 2015-10-21 11:00 +0200
Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> - 2015-10-23 03:50 +0200
Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() Ralf Baechle <ralf@linux-mips.org> - 2015-10-27 15:50 +0100
Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> - 2015-10-27 21:50 +0100
Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() David Daney <ddaney.cavm@gmail.com> - 2015-10-27 22:10 +0100
Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> - 2015-10-27 22:20 +0100
Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> - 2015-10-27 22:50 +0100
Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() Alex Smith <alex@alex-smith.me.uk> - 2015-10-28 11:30 +0100
Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> - 2015-10-28 19:30 +0100
Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() Alex Smith <alex@alex-smith.me.uk> - 2015-10-28 19:40 +0100
Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> - 2015-10-28 20:00 +0100
Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() Alex Smith <alex@alex-smith.me.uk> - 2015-10-28 20:20 +0100
Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> - 2015-10-28 20:30 +0100
Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() Alex Smith <alex@alex-smith.me.uk> - 2015-10-28 21:00 +0100
Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> - 2015-10-28 21:20 +0100
Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() David Daney <ddaney.cavm@gmail.com> - 2015-10-27 22:50 +0100
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