Messages in this thread |  | | From | Arnd Bergmann <> | Date | Mon, 24 Sep 2018 23:08:42 +0200 | Subject | Re: [patch 00/11] x86/vdso: Cleanups, simmplifications and CLOCK_TAI support |
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On Mon, Sep 17, 2018 at 3:00 PM Thomas Gleixner <tglx@linutronix.de> wrote: > > On Fri, 14 Sep 2018, Arnd Bergmann wrote: > > On Fri, Sep 14, 2018 at 2:52 PM Thomas Gleixner <tglx@linutronix.de> wrote: > > A couple of architectures (s390, ia64, riscv, powerpc, arm64) > > implement the vdso as assembler code at the moment, so they > > won't be as easy to consolidate (other than outright replacing all > > the code). > > > > The other five: > > arch/x86/entry/vdso/vclock_gettime.c > > arch/sparc/vdso/vclock_gettime.c > > arch/nds32/kernel/vdso/gettimeofday.c > > arch/mips/vdso/gettimeofday.c > > arch/arm/vdso/vgettimeofday.c > > > > are basically all minor variations of the same code base and could be > > consolidated to some degree. > > Any suggestions here? Should we plan to do that consolitdation based on > > your new version, or just add clock_gettime64 in arm32 and x86-32, and then > > be done with it? The other ones will obviously still be fast for 32-bit time_t > > and will have a working non-vdso sys_clock_getttime64(). > > In principle consolidating all those implementations should be possible to > some extent and probably worthwhile. What's arch specific are the actual > accessors to the hardware clocks.
Ok.
> > I also wonder about clock_getres(): half the architectures seem to implement > > it in vdso, but notably arm32 and x86 don't, and I had not expected it to be > > performance critical given that the result is easily cached in user space. > > getres() is not really performance critical, but adding it does not create > a huge problem either.
Right, I'd just not add a getres_time64() to the vdso then.
Arnd
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