From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
Andy Lutomirski <luto@kernel.org>,
x86@kernel.org, Peter Zijlstra <peterz@infradead.org>,
Matt Rickard <matt@softrans.com.au>,
Stephen Boyd <sboyd@kernel.org>,
John Stultz <john.stultz@linaro.org>,
Florian Weimer <fweimer@redhat.com>,
"K. Y. Srinivasan" <kys@microsoft.com>,
devel@linuxdriverproject.org,
virtualization@lists.linux-foundation.org,
Paolo Bonzini <pbonzini@redhat.com>,
Arnd Bergmann <arnd@arndb.de>, Juergen Gross <jgross@suse.com>
Subject: Re: [patch 10/11] x86/vdso: Move cycle_last handling into the caller
Date: Fri, 14 Sep 2018 17:26:01 +0200 [thread overview]
Message-ID: <874les85iu.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <20180914125118.998589817@linutronix.de> (Thomas Gleixner's message of "Fri, 14 Sep 2018 14:50:16 +0200")
Thomas Gleixner <tglx@linutronix.de> writes:
> Dereferencing gtod->cycle_last all over the place and foing the cycles <
> last comparison in the vclock read functions generates horrible code. Doing
> it at the call site is much better and gains a few cycles both for TSC and
> pvclock.
>
> Caveat: This adds the comparison to the hyperv vclock as well, but I have
> no way to test that.
While the change looks obviously correct for Hyper-V vclock too, by saying
that you encouraged me to give the whole series a shot. I did and turns
out Hyper-V vclock is broken: simple clock_gettime(CLOCK_REALTIME, )
test goes from 70 cpu cycles to 1000 (meaning that we're falling back to
syscall I guess). Bisecting now, stay tuned!
--
Vitaly
next prev parent reply other threads:[~2018-09-14 15:26 UTC|newest]
Thread overview: 157+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-14 12:50 [patch 00/11] x86/vdso: Cleanups, simmplifications and CLOCK_TAI support Thomas Gleixner
2018-09-14 12:50 ` [patch 01/11] clocksource: Provide clocksource_arch_init() Thomas Gleixner
2018-09-14 12:50 ` Thomas Gleixner
2018-09-14 12:50 ` [patch 02/11] x86/time: Implement clocksource_arch_init() Thomas Gleixner
2018-09-14 12:50 ` Thomas Gleixner
2018-09-14 15:45 ` Vitaly Kuznetsov
2018-09-15 6:05 ` Thomas Gleixner
2018-09-15 6:05 ` Thomas Gleixner
2018-09-14 15:45 ` Vitaly Kuznetsov
2018-09-14 12:50 ` [patch 03/11] x86/vdso: Enforce 64bit clocksource Thomas Gleixner
2018-09-14 12:50 ` Thomas Gleixner
2018-09-14 12:50 ` [patch 04/11] x86/vdso: Use unsigned int consistently for vsyscall_gtod_data::seq Thomas Gleixner
2018-09-14 12:50 ` Thomas Gleixner
2018-09-14 12:50 ` [patch 05/11] x86/vdso: Introduce and use vgtod_ts Thomas Gleixner
2018-09-14 12:50 ` Thomas Gleixner
2018-09-14 12:50 ` [patch 06/11] x86/vdso: Collapse high resolution functions Thomas Gleixner
2018-09-14 12:50 ` Thomas Gleixner
2018-09-14 12:50 ` [patch 07/11] x86/vdso: Collapse coarse functions Thomas Gleixner
2018-09-14 12:50 ` Thomas Gleixner
2018-09-14 12:50 ` [patch 08/11] x86/vdso: Replace the clockid switch case Thomas Gleixner
2018-09-14 12:50 ` Thomas Gleixner
2018-09-14 12:50 ` [patch 09/11] x86/vdso: Simplify the invalid vclock case Thomas Gleixner
2018-09-14 12:50 ` Thomas Gleixner
2018-09-17 19:25 ` Andy Lutomirski
2018-09-17 19:25 ` Andy Lutomirski
2018-09-17 20:12 ` John Stultz
2018-09-18 7:52 ` Thomas Gleixner
2018-09-18 7:52 ` Thomas Gleixner
2018-09-18 8:30 ` Peter Zijlstra
2018-09-18 8:30 ` Peter Zijlstra
2018-09-18 8:52 ` Thomas Gleixner
2018-09-18 10:06 ` Thomas Gleixner
2018-09-18 10:41 ` Thomas Gleixner
2018-09-18 10:41 ` Thomas Gleixner
2018-09-18 12:48 ` Peter Zijlstra
2018-09-18 12:48 ` Peter Zijlstra
2018-09-18 13:23 ` Thomas Gleixner
2018-09-18 13:23 ` Thomas Gleixner
2018-09-18 13:38 ` Peter Zijlstra
2018-09-18 13:38 ` Peter Zijlstra
2018-09-18 15:52 ` Thomas Gleixner
2018-09-18 15:52 ` Thomas Gleixner
2018-09-27 14:41 ` Thomas Gleixner
2018-09-27 14:41 ` Thomas Gleixner
2018-09-18 10:06 ` Thomas Gleixner
2018-09-18 8:52 ` Thomas Gleixner
2018-09-18 14:01 ` Andy Lutomirski
2018-09-18 14:01 ` Andy Lutomirski
2018-09-18 22:46 ` Thomas Gleixner
2018-09-18 22:46 ` Thomas Gleixner
2018-09-18 23:03 ` Andy Lutomirski
2018-09-18 23:03 ` Andy Lutomirski
2018-09-18 23:16 ` Thomas Gleixner
2018-09-27 14:36 ` Thomas Gleixner
2018-09-27 14:36 ` Thomas Gleixner
2018-09-27 14:39 ` Andy Lutomirski
2018-09-27 14:39 ` Andy Lutomirski
2018-09-18 23:16 ` Thomas Gleixner
2018-09-19 9:08 ` Rasmus Villemoes
2018-09-19 13:29 ` Thomas Gleixner
2018-09-19 13:29 ` Thomas Gleixner
2018-09-14 12:50 ` [patch 10/11] x86/vdso: Move cycle_last handling into the caller Thomas Gleixner
2018-09-14 12:50 ` Thomas Gleixner
2018-09-14 15:26 ` Vitaly Kuznetsov
2018-09-14 15:26 ` Vitaly Kuznetsov [this message]
2018-09-14 12:50 ` [patch 11/11] x66/vdso: Add CLOCK_TAI support Thomas Gleixner
2018-09-14 14:04 ` Andy Lutomirski
2018-09-14 14:04 ` Andy Lutomirski
2018-09-14 14:27 ` Thomas Gleixner
2018-09-14 14:27 ` Thomas Gleixner
2018-09-14 14:59 ` Andy Lutomirski
2018-09-16 9:39 ` Thomas Gleixner
2018-09-16 9:39 ` Thomas Gleixner
2018-09-14 14:59 ` Andy Lutomirski
2018-09-14 12:50 ` Thomas Gleixner
2018-09-14 12:56 ` [patch 00/11] x86/vdso: Cleanups, simmplifications and " Florian Weimer
2018-09-14 13:05 ` Thomas Gleixner
2018-09-14 13:05 ` Thomas Gleixner
2018-09-14 13:06 ` Florian Weimer
2018-09-14 13:19 ` Thomas Gleixner
2018-09-14 13:19 ` Thomas Gleixner
2018-09-14 13:09 ` Peter Zijlstra
2018-09-14 13:09 ` Peter Zijlstra
2018-09-14 14:22 ` Arnd Bergmann
2018-09-14 14:22 ` Arnd Bergmann
2018-09-17 13:00 ` Thomas Gleixner
2018-09-24 21:08 ` Arnd Bergmann
2018-09-24 21:08 ` Arnd Bergmann
2018-09-17 13:00 ` Thomas Gleixner
2018-10-03 5:15 ` Andy Lutomirski
2018-10-03 5:15 ` Andy Lutomirski
2018-10-03 9:22 ` Vitaly Kuznetsov
2018-10-03 10:20 ` Andy Lutomirski
2018-10-03 10:20 ` Andy Lutomirski
2018-10-03 12:01 ` Vitaly Kuznetsov
2018-10-03 12:01 ` Vitaly Kuznetsov
2018-10-03 14:20 ` Andy Lutomirski
2018-10-03 15:10 ` Thomas Gleixner
2018-10-03 16:18 ` Andy Lutomirski
2018-10-03 16:18 ` Andy Lutomirski
2018-10-03 15:10 ` Thomas Gleixner
2018-10-03 14:20 ` Andy Lutomirski
2018-10-03 19:06 ` Marcelo Tosatti
2018-10-03 19:06 ` Marcelo Tosatti
2018-10-04 7:54 ` Vitaly Kuznetsov
2018-10-04 8:11 ` Peter Zijlstra
2018-10-04 8:11 ` Peter Zijlstra
2018-10-04 14:00 ` Andy Lutomirski
2018-10-04 14:00 ` Andy Lutomirski
2018-10-04 19:31 ` Peter Zijlstra
2018-10-04 19:31 ` Peter Zijlstra
2018-10-04 20:05 ` Andy Lutomirski
2018-10-04 20:05 ` Andy Lutomirski
2018-10-04 22:15 ` Andy Lutomirski
2018-10-04 22:15 ` Andy Lutomirski
2018-10-06 20:27 ` Marcelo Tosatti
2018-10-06 20:27 ` Marcelo Tosatti
2018-10-06 22:28 ` Andy Lutomirski
2018-10-08 15:26 ` Marcelo Tosatti
2018-10-08 15:26 ` Marcelo Tosatti
2018-10-08 17:38 ` Andy Lutomirski
2018-10-08 17:38 ` Andy Lutomirski
2018-10-08 19:36 ` Marcelo Tosatti
2018-10-08 19:36 ` Marcelo Tosatti
2018-10-09 20:09 ` Andy Lutomirski
2018-10-11 22:27 ` Marcelo Tosatti
2018-10-11 22:27 ` Marcelo Tosatti
2018-10-11 23:00 ` Andy Lutomirski
2018-10-11 23:00 ` Andy Lutomirski
2018-10-15 13:39 ` Marcelo Tosatti
2018-10-15 13:39 ` Marcelo Tosatti
2018-10-09 20:09 ` Andy Lutomirski
2018-10-06 22:28 ` Andy Lutomirski
2018-10-06 20:49 ` Marcelo Tosatti
2018-10-06 20:49 ` Marcelo Tosatti
2018-10-04 12:00 ` Paolo Bonzini
2018-10-04 14:04 ` Andy Lutomirski
2018-10-04 14:04 ` Andy Lutomirski
2018-10-04 12:00 ` Paolo Bonzini
2018-10-05 21:18 ` Marcelo Tosatti
2018-10-05 21:18 ` Marcelo Tosatti
2018-10-04 7:54 ` Vitaly Kuznetsov
2018-10-03 9:22 ` Vitaly Kuznetsov
2018-10-03 19:00 ` Marcelo Tosatti
2018-10-03 19:00 ` Marcelo Tosatti
2018-10-03 19:05 ` [patch 00/11] x86/vdso: Cleanups, simmplifications and CLOCK_TAI support\ Marcelo Tosatti
2018-10-03 19:05 ` Marcelo Tosatti
2018-10-03 22:32 ` [patch 00/11] x86/vdso: Cleanups, simmplifications and CLOCK_TAI support Andy Lutomirski
2018-10-03 22:32 ` Andy Lutomirski
2018-10-04 16:37 ` Marcelo Tosatti
2018-10-04 17:08 ` Andy Lutomirski
2018-10-04 17:28 ` Vitaly Kuznetsov
2018-10-04 17:28 ` Vitaly Kuznetsov
2018-10-04 17:08 ` Andy Lutomirski
2018-10-04 16:37 ` Marcelo Tosatti
2018-10-04 20:32 ` Andy Lutomirski
2018-10-04 20:32 ` Andy Lutomirski
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