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Groups > linux.kernel > #1671493 > unrolled thread
| Started by | Zhenzhong Duan <zhenzhong.duan@oracle.com> |
|---|---|
| First post | 2017-06-21 10:30 +0200 |
| Last post | 2017-06-22 16:10 +0200 |
| Articles | 4 — 3 participants |
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[PATCH RESEND] Calling check_system_tsc_reliable() before unsynchronized_tsc() Zhenzhong Duan <zhenzhong.duan@oracle.com> - 2017-06-21 10:30 +0200
Re: [PATCH RESEND] Calling check_system_tsc_reliable() before unsynchronized_tsc() Thomas Gleixner <tglx@linutronix.de> - 2017-06-22 16:00 +0200
Re: [PATCH RESEND] Calling check_system_tsc_reliable() before unsynchronized_tsc() Zhenzhong Duan <zhenzhong.duan@oracle.com> - 2017-06-23 10:40 +0200
[tip:x86/timers] x86/tsc: Call check_system_tsc_reliable() before unsynchronized_tsc() tip-bot for Zhenzhong Duan <tipbot@zytor.com> - 2017-06-22 16:10 +0200
| From | Zhenzhong Duan <zhenzhong.duan@oracle.com> |
|---|---|
| Date | 2017-06-21 10:30 +0200 |
| Subject | [PATCH RESEND] Calling check_system_tsc_reliable() before unsynchronized_tsc() |
| Message-ID | <tUJbr-3H5-1@gated-at.bofh.it> |
unsynchronized_tsc() checks value of tsc_clocksource_reliable which is set by
check_system_tsc_reliable(). It's better to move check_system_tsc_reliable() at
front.
Though X86_FEATURE_CONSTANT_TSC is usually set for TSC reliable system, just in
case.
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
---
arch/x86/kernel/tsc.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 714dfba..a316bdd 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -1412,11 +1412,11 @@ void __init tsc_init(void)
use_tsc_delay();
+ check_system_tsc_reliable();
+
if (unsynchronized_tsc())
mark_tsc_unstable("TSCs unsynchronized");
- check_system_tsc_reliable();
-
detect_art();
}
--
1.7.3
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| From | Thomas Gleixner <tglx@linutronix.de> |
|---|---|
| Date | 2017-06-22 16:00 +0200 |
| Message-ID | <tVaOl-5tA-1@gated-at.bofh.it> |
| In reply to | #1671493 |
Zhenzhong, On Wed, 21 Jun 2017, Zhenzhong Duan wrote: So the patch format is now correct, but the subject line is missing a proper subsystem prefix. Please use 'git log 'path/to/patched/file' next time to see what the usually used prefix for a file is. In this case it's: x86/tsc Also please do not use [PATCH RESEND] when your patch is different from the version you sent before. Please use [PATCH v2] instead. > unsynchronized_tsc() checks value of tsc_clocksource_reliable which is set by > check_system_tsc_reliable(). It's better to move check_system_tsc_reliable() at > front. Please make your statements affirmative. 'It's better' is a weak expression. > Though X86_FEATURE_CONSTANT_TSC is usually set for TSC reliable system, just in > case. So what you wanted to say here is: tsc_clocksource_reliable is initialized in check_system_tsc_reliable(), but it is checked in unsynchronized_tsc() which is called before the initialization. In practice that's not an issue because systems which mark the TSC reliable have X86_FEATURE_CONSTANT_TSC set as well, which is evaluated in unsynchronized_tsc() before tsc_clocksource_reliable. Reorder the calls so initialization happens before usage. All this information is also documented in Documentation/process/. No need to resend. I'll fix it up for you this time. Thanks, tglx
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| From | Zhenzhong Duan <zhenzhong.duan@oracle.com> |
|---|---|
| Date | 2017-06-23 10:40 +0200 |
| Message-ID | <tVsid-8gZ-3@gated-at.bofh.it> |
| In reply to | #1672648 |
在 2017/6/22 21:56, Thomas Gleixner 写道: > Zhenzhong, > > On Wed, 21 Jun 2017, Zhenzhong Duan wrote: > > So the patch format is now correct, but the subject line is missing a > proper subsystem prefix. Please use 'git log 'path/to/patched/file' next > time to see what the usually used prefix for a file is. > > In this case it's: x86/tsc > > Also please do not use [PATCH RESEND] when your patch is different from the > version you sent before. Please use [PATCH v2] instead. Got it. > >> unsynchronized_tsc() checks value of tsc_clocksource_reliable which is set by >> check_system_tsc_reliable(). It's better to move check_system_tsc_reliable() at >> front. > Please make your statements affirmative. 'It's better' is a weak expression. > >> Though X86_FEATURE_CONSTANT_TSC is usually set for TSC reliable system, just in >> case. > So what you wanted to say here is: > > tsc_clocksource_reliable is initialized in check_system_tsc_reliable(), > but it is checked in unsynchronized_tsc() which is called before the > initialization. > > In practice that's not an issue because systems which mark the TSC > reliable have X86_FEATURE_CONSTANT_TSC set as well, which is evaluated > in unsynchronized_tsc() before tsc_clocksource_reliable. > > Reorder the calls so initialization happens before usage. Exactly. > > All this information is also documented in Documentation/process/. I'll read them. > > No need to resend. I'll fix it up for you this time. Ok, thanks. zduan
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| From | tip-bot for Zhenzhong Duan <tipbot@zytor.com> |
|---|---|
| Date | 2017-06-22 16:10 +0200 |
| Subject | [tip:x86/timers] x86/tsc: Call check_system_tsc_reliable() before unsynchronized_tsc() |
| Message-ID | <tVaY2-5Mw-21@gated-at.bofh.it> |
| In reply to | #1671493 |
Commit-ID: a1272dd5531b259bf7313ac7597a67362698038c
Gitweb: http://git.kernel.org/tip/a1272dd5531b259bf7313ac7597a67362698038c
Author: Zhenzhong Duan <zhenzhong.duan@oracle.com>
AuthorDate: Wed, 21 Jun 2017 01:23:37 -0700
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 22 Jun 2017 16:00:03 +0200
x86/tsc: Call check_system_tsc_reliable() before unsynchronized_tsc()
tsc_clocksource_reliable is initialized in check_system_tsc_reliable(), but
it is checked in unsynchronized_tsc() which is called before the
initialization.
In practice that's not an issue because systems which mark the TSC
reliable have X86_FEATURE_CONSTANT_TSC set as well, which is evaluated
in unsynchronized_tsc() before tsc_clocksource_reliable.
Reorder the calls so initialization happens before usage.
[ tglx: Massaged changelog ]
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/b1532ef7-cd9f-45f7-9f49-48dd2a5c2495@default
---
arch/x86/kernel/tsc.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 714dfba..a316bdd 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -1412,11 +1412,11 @@ void __init tsc_init(void)
use_tsc_delay();
+ check_system_tsc_reliable();
+
if (unsynchronized_tsc())
mark_tsc_unstable("TSCs unsynchronized");
- check_system_tsc_reliable();
-
detect_art();
}
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