similar to: [PATCH RFC 0/2] x86/vdso: Add Hyper-V TSC page clocksource support

On Wed, Feb 8, 2017 at 9:07 AM, Vitaly Kuznetsov <vkuznets at redhat.com> wrote: > Hyper-V TSC page clocksource is suitable for vDSO, however, the protocol > defined by the hypervisor is different from VCLOCK_PVCLOCK. Implement the > required support re-using pvclock_page VVAR as VCLOCK_PVCLOCK is mutually > exclusive with VCLOCK_HVCLOCK at run time. > > Signed-off-by:

On Wed, Feb 8, 2017 at 9:07 AM, Vitaly Kuznetsov <vkuznets at redhat.com> wrote: > Hyper-V TSC page clocksource is suitable for vDSO, however, the protocol > defined by the hypervisor is different from VCLOCK_PVCLOCK. Implement the > required support re-using pvclock_page VVAR as VCLOCK_PVCLOCK is mutually > exclusive with VCLOCK_HVCLOCK at run time. > > Signed-off-by:

Hyper-V TSC page clocksource is suitable for vDSO, however, the protocol defined by the hypervisor is different from VCLOCK_PVCLOCK. Implement the required support re-using pvclock_page VVAR as VCLOCK_PVCLOCK is mutually exclusive with VCLOCK_HVCLOCK at run time. Signed-off-by: Vitaly Kuznetsov <vkuznets at redhat.com> --- arch/x86/entry/vdso/vclock_gettime.c | 48

Hi, Hyper-V TSC page clocksource is suitable for vDSO, however, the protocol defined by the hypervisor is different from VCLOCK_PVCLOCK. Implemented the required support. Simple sysbench test shows the following results: Before: # time sysbench --test=memory --max-requests=500000 run ... real 1m22.618s user 0m50.193s sys 0m32.268s After: # time sysbench --test=memory

Hi, Hyper-V TSC page clocksource is suitable for vDSO, however, the protocol defined by the hypervisor is different from VCLOCK_PVCLOCK. Implemented the required support. Simple sysbench test shows the following results: Before: # time sysbench --test=memory --max-requests=500000 run ... real 1m22.618s user 0m50.193s sys 0m32.268s After: # time sysbench --test=memory

Hi, merge window is about to close so I hope it's OK to make another try here. Changes since v2: - Add explicit READ_ONCE() to not rely on 'volatile' [Andy Lutomirski] - rdtsc() -> rdtsc_ordered() [Andy Lutomirski] - virt_rmb() -> smp_rmb() [Thomas Gleixner, Andy Lutomirski] Thomas, Andy, it seems the only blocker for the series was the ambiguity with TSC page read algorithm.

Hi, merge window is about to close so I hope it's OK to make another try here. Changes since v2: - Add explicit READ_ONCE() to not rely on 'volatile' [Andy Lutomirski] - rdtsc() -> rdtsc_ordered() [Andy Lutomirski] - virt_rmb() -> smp_rmb() [Thomas Gleixner, Andy Lutomirski] Thomas, Andy, it seems the only blocker for the series was the ambiguity with TSC page read algorithm.

Hi, while we're still waiting for a definitive ACK from Microsoft that the algorithm is good for SMP case (as we can't prevent the code in vdso from migrating between CPUs) I'd like to send v2 with some modifications to keep the discussion going. Changes since v1: - Document the TSC page reading protocol [Thomas Gleixner]. - Separate the TSC page reading code from

Hi, while we're still waiting for a definitive ACK from Microsoft that the algorithm is good for SMP case (as we can't prevent the code in vdso from migrating between CPUs) I'd like to send v2 with some modifications to keep the discussion going. Changes since v1: - Document the TSC page reading protocol [Thomas Gleixner]. - Separate the TSC page reading code from

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 problematic as the compiler tends to generate a jump table which then requires to use retpolines. If jump tables are disabled it adds yet another conditional to the existing

Re-use the therm-exported fan structure with only two minor modifications: - pwm_freq: u16 -> u32; - add fan_type (toggle or PWM) v2: - Do not memset the table to 0 as it erases the pre-set default values Signed-off-by: Martin Peres <martin.peres at free.fr> --- drm/Kbuild | 1 + drm/core/include/subdev/bios/fan.h | 1 + drm/core/subdev/bios/fan.c | 1

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 problematic as the compiler tends to generate a jump table which then requires to use retpolines. If jump tables are disabled it adds yet another conditional to the existing

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 problematic as the compiler tends to generate a jump table which then requires to use retpolines. If jump tables are disabled it adds yet another conditional to the existing

On Thu, 9 Feb 2017, Vitaly Kuznetsov wrote: > +#ifdef CONFIG_HYPERV_TSCPAGE > +static notrace u64 vread_hvclock(int *mode) > +{ > + const struct ms_hyperv_tsc_page *tsc_pg = > + (const struct ms_hyperv_tsc_page *)&hvclock_page; > + u64 sequence, scale, offset, current_tick, cur_tsc; > + > + while (1) { > + sequence = READ_ONCE(tsc_pg->tsc_sequence); > + if

On Thu, 9 Feb 2017, Vitaly Kuznetsov wrote: > +#ifdef CONFIG_HYPERV_TSCPAGE > +static notrace u64 vread_hvclock(int *mode) > +{ > + const struct ms_hyperv_tsc_page *tsc_pg = > + (const struct ms_hyperv_tsc_page *)&hvclock_page; > + u64 sequence, scale, offset, current_tick, cur_tsc; > + > + while (1) { > + sequence = READ_ONCE(tsc_pg->tsc_sequence); > + if

On Thu, Feb 9, 2017 at 12:45 PM, KY Srinivasan <kys at microsoft.com> wrote: > > >> -----Original Message----- >> From: Thomas Gleixner [mailto:tglx at linutronix.de] >> Sent: Thursday, February 9, 2017 9:08 AM >> To: Vitaly Kuznetsov <vkuznets at redhat.com> >> Cc: x86 at kernel.org; Andy Lutomirski <luto at amacapital.net>; Ingo Molnar

On Thu, Feb 9, 2017 at 12:45 PM, KY Srinivasan <kys at microsoft.com> wrote: > > >> -----Original Message----- >> From: Thomas Gleixner [mailto:tglx at linutronix.de] >> Sent: Thursday, February 9, 2017 9:08 AM >> To: Vitaly Kuznetsov <vkuznets at redhat.com> >> Cc: x86 at kernel.org; Andy Lutomirski <luto at amacapital.net>; Ingo Molnar

The actual code looks fine, but the style police will not like you. { should be at start of line on functions. And #else should be at start of line, But maybe this was just more of exchange mangling the mail. -----Original Message----- From: Vitaly Kuznetsov [mailto:vkuznets at redhat.com] Sent: Thursday, February 9, 2017 6:11 AM To: x86 at kernel.org; Andy Lutomirski <luto at

The actual code looks fine, but the style police will not like you. { should be at start of line on functions. And #else should be at start of line, But maybe this was just more of exchange mangling the mail. -----Original Message----- From: Vitaly Kuznetsov [mailto:vkuznets at redhat.com] Sent: Thursday, February 9, 2017 6:11 AM To: x86 at kernel.org; Andy Lutomirski <luto at

The code flow for the vclocks is convoluted as it requires the vclocks which can be invalidated separately from the vsyscall_gtod_data sequence to store the fact in a separate variable. That's inefficient. Restructure the code so the vclock readout returns cycles and the conversion to nanoseconds is handled at the call site. If the clock gets invalidated or vclock is already VCLOCK_NONE,