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From: Thomas Gleixner <tglx@linutronix.de>
To: kan.liang@linux.intel.com, jstultz@google.com,
	peterz@infradead.org, mingo@redhat.com,
	linux-kernel@vger.kernel.org
Cc: sboyd@kernel.org, eranian@google.com, namhyung@kernel.org,
	ak@linux.intel.com, adrian.hunter@intel.com,
	Kan Liang <kan.liang@linux.intel.com>,
	Ravi Bangoria <ravi.bangoria@amd.com>
Subject: Re: [RFC PATCH V2 4/9] perf/x86: Enable post-processing monotonic raw conversion
Date: Tue, 14 Feb 2023 21:02:23 +0100	[thread overview]
Message-ID: <875yc4rp68.ffs@tglx> (raw)
In-Reply-To: <20230213190754.1836051-5-kan.liang@linux.intel.com>

Kan!

On Mon, Feb 13 2023 at 11:07, kan liang wrote:
> From: Kan Liang <kan.liang@linux.intel.com>
> +	} else if (perf_event_hw_time(event)) {
> +		struct ktime_conv mono;
> +
> +		userpg->cap_user_time_mono_raw = 1;
> +		ktime_get_fast_mono_raw_conv(&mono);

What guarantees that the clocksource used by the timekeeping core is
actually TSC? Nothing at all. You cannot make assumptions here.

Thanks,

        tglx

  reply	other threads:[~2023-02-14 20:02 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-13 19:07 [RFC PATCH V2 0/9] Convert TSC to monotonic raw clock for PEBS kan.liang
2023-02-13 19:07 ` [RFC PATCH V2 1/9] timekeeping: Expose the conversion information of monotonic raw kan.liang
2023-02-13 19:28   ` John Stultz
2023-02-13 19:07 ` [RFC PATCH V2 2/9] perf: Extend ABI to support post-processing monotonic raw conversion kan.liang
2023-02-13 19:37   ` John Stultz
2023-02-13 21:40     ` Liang, Kan
2023-02-13 22:22       ` John Stultz
2023-02-14 10:43         ` Peter Zijlstra
2023-02-14 17:46           ` Liang, Kan
2023-02-14 19:37             ` John Stultz
2023-02-14 20:09               ` Liang, Kan
2023-02-14 20:21                 ` John Stultz
2023-03-12 20:50                   ` Andi Kleen
2023-02-14 19:34           ` John Stultz
2023-02-14 14:51         ` Liang, Kan
2023-02-14 17:00           ` Liang, Kan
2023-02-14 20:11             ` John Stultz
2023-02-14 20:38               ` Liang, Kan
2023-02-17 23:11                 ` John Stultz
2023-03-08 18:44                   ` Liang, Kan
2023-03-09  1:17                     ` John Stultz
2023-03-09 16:56                       ` Liang, Kan
2023-03-11  5:55                         ` John Stultz
2023-03-13 21:19                           ` Liang, Kan
2023-03-18  6:02                             ` John Stultz
2023-03-21 15:26                               ` Liang, Kan
2023-02-14 19:52           ` John Stultz
2023-02-13 19:07 ` [RFC PATCH V2 3/9] perf/x86: Factor out x86_pmu_sample_preload() kan.liang
2023-02-13 19:07 ` [RFC PATCH V2 4/9] perf/x86: Enable post-processing monotonic raw conversion kan.liang
2023-02-14 20:02   ` Thomas Gleixner [this message]
2023-02-14 20:21     ` Liang, Kan
2023-02-14 20:55       ` Thomas Gleixner
2023-03-21 15:38         ` Liang, Kan
2023-02-13 19:07 ` [RFC PATCH V2 5/9] perf/x86/intel: Enable large PEBS for monotonic raw kan.liang
2023-02-13 19:07 ` [RFC PATCH V2 6/9] tools headers UAPI: Sync linux/perf_event.h with the kernel sources kan.liang
2023-02-13 19:07 ` [RFC PATCH V2 7/9] perf session: Support the monotonic raw clock conversion information kan.liang
2023-02-13 19:07 ` [RFC PATCH V2 8/9] perf evsel, tsc: Support the monotonic raw clock conversion kan.liang
2023-02-13 19:07 ` [RFC PATCH V2 9/9] perf evsel: Enable post-processing monotonic raw conversion by default kan.liang

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