Re: [patch 00/11] x86/vdso: Cleanups, simmplifications and CLOCK_TAI support

2018-10-04 Thread Andy Lutomirski
On Thu, Oct 4, 2018 at 9:43 AM Marcelo Tosatti wrote: > > On Wed, Oct 03, 2018 at 03:32:08PM -0700, Andy Lutomirski wrote: > > On Wed, Oct 3, 2018 at 12:01 PM Marcelo Tosatti wrote: > > > > > > On Tue, Oct 02, 2018 at 10:15:49PM -0700, Andy Lutomirski wrote: > > > > Hi Vitaly, Paolo, Radim,

Re: [patch 00/11] x86/vdso: Cleanups, simmplifications and CLOCK_TAI support

2018-10-04 Thread Marcelo Tosatti
On Wed, Oct 03, 2018 at 03:32:08PM -0700, Andy Lutomirski wrote: > On Wed, Oct 3, 2018 at 12:01 PM Marcelo Tosatti wrote: > > > > On Tue, Oct 02, 2018 at 10:15:49PM -0700, Andy Lutomirski wrote: > > > Hi Vitaly, Paolo, Radim, etc., > > > > > > On Fri, Sep 14, 2018 at 5:52 AM Thomas Gleixner > >

Re: [patch 00/11] x86/vdso: Cleanups, simmplifications and CLOCK_TAI support

2018-10-04 Thread Vitaly Kuznetsov
Andy Lutomirski writes: > On Thu, Oct 4, 2018 at 9:43 AM Marcelo Tosatti wrote: >> >> On Wed, Oct 03, 2018 at 03:32:08PM -0700, Andy Lutomirski wrote: >> > On Wed, Oct 3, 2018 at 12:01 PM Marcelo Tosatti >> > wrote: >> > > >> > > On Tue, Oct 02, 2018 at 10:15:49PM -0700, Andy Lutomirski

Re: [patch 00/11] x86/vdso: Cleanups, simmplifications and CLOCK_TAI support

2018-10-04 Thread Andy Lutomirski
On Fri, Sep 14, 2018 at 5:52 AM Thomas Gleixner wrote: > > Matt attempted to add CLOCK_TAI support to the VDSO clock_gettime() > implementation, which extended the clockid switch case and added yet > another slightly different copy of the same code. > > Especially the extended switch case is

Re: [patch 00/11] x86/vdso: Cleanups, simmplifications and CLOCK_TAI support

2018-10-04 Thread Andy Lutomirski
> On Oct 4, 2018, at 12:31 PM, Peter Zijlstra wrote: > > On Thu, Oct 04, 2018 at 07:00:45AM -0700, Andy Lutomirski wrote: >>> On Oct 4, 2018, at 1:11 AM, Peter Zijlstra wrote: >>> On Thu, Oct 04, 2018 at 09:54:45AM +0200, Vitaly Kuznetsov wrote: I was hoping to hear this from you

Re: [patch 00/11] x86/vdso: Cleanups, simmplifications and CLOCK_TAI support

2018-10-04 Thread Peter Zijlstra
On Thu, Oct 04, 2018 at 07:00:45AM -0700, Andy Lutomirski wrote: > > On Oct 4, 2018, at 1:11 AM, Peter Zijlstra wrote: > > > >> On Thu, Oct 04, 2018 at 09:54:45AM +0200, Vitaly Kuznetsov wrote: > >> I was hoping to hear this from you :-) If I am to suggest how we can > >> move forward I'd

Re: [patch 00/11] x86/vdso: Cleanups, simmplifications and CLOCK_TAI support

2018-10-04 Thread Andy Lutomirski
For better or for worse, I'm trying to understand this code. So far, I've come up with this patch: https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git/commit/?h=x86/vdso-tglx=14fd71e12b1c4492a06f368f75041f263e6862bf Is it correct, or am I missing some subtlety?

Re: [patch 00/11] x86/vdso: Cleanups, simmplifications and CLOCK_TAI support

2018-10-04 Thread Peter Zijlstra
On Thu, Oct 04, 2018 at 09:54:45AM +0200, Vitaly Kuznetsov wrote: > I was hoping to hear this from you :-) If I am to suggest how we can > move forward I'd propose: > - Check if pure TSC can be used on SkyLake+ systems (where TSC scaling > is supported). > - Check if non-masterclock mode is still

Re: [patch 00/11] x86/vdso: Cleanups, simmplifications and CLOCK_TAI support

2018-10-04 Thread Vitaly Kuznetsov
Marcelo Tosatti writes: > On Wed, Oct 03, 2018 at 11:22:58AM +0200, Vitaly Kuznetsov wrote: >> >> There is a very long history of different (hardware) issues Marcelo was >> fighting with and the current code is the survived Frankenstein. > > Right, the code has to handle different TSC modes. >

Re: [patch 00/11] x86/vdso: Cleanups, simmplifications and CLOCK_TAI support

2018-10-04 Thread Paolo Bonzini
On 04/10/2018 09:54, Vitaly Kuznetsov wrote: > - Check if pure TSC can be used on SkyLake+ systems (where TSC scaling > is supported). Not if you want to migrate to pre-Skylake systems. > - Check if non-masterclock mode is still needed. E.g. HyperV's TSC page > clocksource is a single page for

Re: [patch 00/11] x86/vdso: Cleanups, simmplifications and CLOCK_TAI support

2018-10-04 Thread Andy Lutomirski
> On Oct 4, 2018, at 1:11 AM, Peter Zijlstra wrote: > >> On Thu, Oct 04, 2018 at 09:54:45AM +0200, Vitaly Kuznetsov wrote: >> I was hoping to hear this from you :-) If I am to suggest how we can >> move forward I'd propose: >> - Check if pure TSC can be used on SkyLake+ systems (where TSC

Re: [patch 00/11] x86/vdso: Cleanups, simmplifications and CLOCK_TAI support

2018-10-04 Thread Andy Lutomirski
> On Oct 4, 2018, at 5:00 AM, Paolo Bonzini wrote: > >> On 04/10/2018 09:54, Vitaly Kuznetsov wrote: >> - Check if pure TSC can be used on SkyLake+ systems (where TSC scaling >> is supported). > > Not if you want to migrate to pre-Skylake systems. > >> - Check if non-masterclock mode is still