linux-kernel - Re: [PATCH] x86/vdso: Use non-serializing instruction rdtsc

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Message-ID: <tencent_84FB1255E5E4157DD418B1DBA0418832AB05@qq.com>
Date:   Wed, 17 May 2023 08:41:31 +0800
From:   Rong Tao <rtoax@...mail.com>
To:     rtoax@...mail.com, dave.hansen@...ux.intel.com, hpa@...or.com,
        tglx@...utronix.de, luto@...nel.org
Cc:     bp@...en8.de, linux-kernel@...r.kernel.org, mingo@...hat.com,
        rongtao@...tc.cn, x86@...nel.org
Subject: Re: [PATCH] x86/vdso: Use non-serializing instruction rdtsc

Thank you all very much for your responses, I tested the test code
evil-clock-test[0] provided by Andy, this patch does cause time read errors
and load errors.

    $ ./evil-clock-test.out -c monotonic
    CPU vendor   : GenuineIntel
    CPU model    : Intel(R) Core(TM) i7-10710U CPU @ 1.10GHz
    CPU stepping : 0
    TSC flags    : tsc rdtscp constant_tsc tsc_known_freq tsc_deadline_timer tsc_adjust
    Will test the "CLOCK_MONOTONIC" clock.
    Now test failed  : worst error 255 with 81902816 samples
    Load3 test failed: worst error 384 with 3284297 samples
    Load test passed : margin 32 with 18848374 samples
    Store test failed as expected: worst error 704 with 18213325 samples

Thanks again :)

[0] https://git.kernel.org/pub/scm/linux/kernel/git/luto/misc-tests.git/tree/evil-clock-test.cc