Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [PATCH v0.9.1 3/6] sched/umcg: implement UMCG syscalls | Date | Fri, 26 Nov 2021 22:11:17 +0100 |
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On Wed, Nov 24 2021 at 22:19, Peter Zijlstra wrote: > On Mon, Nov 22, 2021 at 01:13:24PM -0800, Peter Oskolkov wrote: > >> + * Timestamp: a 46-bit CLOCK_MONOTONIC timestamp, at 16ns resolution. > >> +static int umcg_update_state(u64 __user *state_ts, u64 *expected, u64 desired, >> + bool may_fault) >> +{ >> + u64 curr_ts = (*expected) >> (64 - UMCG_STATE_TIMESTAMP_BITS); >> + u64 next_ts = ktime_get_ns() >> UMCG_STATE_TIMESTAMP_GRANULARITY; > > I'm still very hesitant to use ktime (fear the HPET); but I suppose it > makes sense to use a time base that's accessible to userspace. Was > MONOTONIC_RAW considered?
MONOTONIC_RAW is not really useful as you can't sleep on it and it won't solve the HPET crap either.
Thanks,
tglx
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