From: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
To: Markos Chandras <markos.chandras@imgtec.com>,
<linux-mips@linux-mips.org>
Cc: Alex Smith <alex.smith@imgtec.com>, <linux-kernel@vger.kernel.org>
Subject: Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime()
Date: Thu, 22 Oct 2015 18:41:30 -0700 [thread overview]
Message-ID: <5629904A.2070400@imgtec.com> (raw)
In-Reply-To: <1445417864-31453-1-git-send-email-markos.chandras@imgtec.com>
You can not use R4K CP0_count in SMP (multicore) without core-specific
adjustment.
After first power-saving with core clock off or core down the values in
CP0_count
in different cores are absolutely different.
Until you include in system a patch like
http://patchwork.linux-mips.org/patch/10871/
"MIPS: Setup an instruction emulation in VDSO protected page
instead of user stack"
which creates a per-thread memory and put into that memory an adjustment
value
(which can be changed during re-schedule to another core), the use of
R4K counter is incorrect
in SMP environment.
Note: It is also possible to setup and maintain a per-core page with
that value too as
an alternative variant for adjustment.
WARNING: multiple messages have this Message-ID (diff)
From: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
To: Markos Chandras <markos.chandras@imgtec.com>, linux-mips@linux-mips.org
Cc: Alex Smith <alex.smith@imgtec.com>, linux-kernel@vger.kernel.org
Subject: Re: [v3, 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime()
Date: Thu, 22 Oct 2015 18:41:30 -0700 [thread overview]
Message-ID: <5629904A.2070400@imgtec.com> (raw)
Message-ID: <20151023014130.HRjgYi7x2GJbf6FbCi36tcMrlULcdDcfnOEndUGR8Jg@z> (raw)
In-Reply-To: <1445417864-31453-1-git-send-email-markos.chandras@imgtec.com>
You can not use R4K CP0_count in SMP (multicore) without core-specific
adjustment.
After first power-saving with core clock off or core down the values in
CP0_count
in different cores are absolutely different.
Until you include in system a patch like
http://patchwork.linux-mips.org/patch/10871/
"MIPS: Setup an instruction emulation in VDSO protected page
instead of user stack"
which creates a per-thread memory and put into that memory an adjustment
value
(which can be changed during re-schedule to another core), the use of
R4K counter is incorrect
in SMP environment.
Note: It is also possible to setup and maintain a per-core page with
that value too as
an alternative variant for adjustment.
next prev parent reply other threads:[~2015-10-23 1:41 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-28 10:03 [PATCH 0/3] MIPS VDSO support Markos Chandras
2015-09-28 10:03 ` Markos Chandras
2015-09-28 10:10 ` [PATCH 1/3] MIPS: Initial implementation of a VDSO Markos Chandras
2015-09-28 10:10 ` Markos Chandras
2015-09-28 10:54 ` Alex Smith
2015-09-28 13:07 ` Matthew Fortune
2015-09-28 13:07 ` Matthew Fortune
2015-11-20 18:15 ` Maciej W. Rozycki
2015-10-09 8:05 ` [PATCH v2 " Markos Chandras
2015-10-09 8:05 ` Markos Chandras
2015-10-21 8:54 ` [PATCH v3 " Markos Chandras
2015-10-21 8:54 ` Markos Chandras
2015-09-28 10:11 ` [PATCH 2/3] irqchip: irq-mips-gic: Provide function to map GIC user section Markos Chandras
2015-09-28 10:11 ` Markos Chandras
2015-09-28 10:55 ` Marc Zyngier
2015-09-28 14:16 ` Qais Yousef
2015-09-28 14:16 ` Qais Yousef
2015-09-28 15:03 ` Marc Zyngier
2015-10-05 8:22 ` Markos Chandras
2015-10-05 8:22 ` Markos Chandras
2015-10-12 9:40 ` [PATCH v2 " Markos Chandras
2015-10-12 9:40 ` Markos Chandras
2015-10-12 9:51 ` Marc Zyngier
2015-10-12 10:16 ` Thomas Gleixner
2015-10-15 9:37 ` Qais Yousef
2015-10-15 9:37 ` Qais Yousef
2015-10-15 10:18 ` Thomas Gleixner
2015-09-28 10:12 ` [PATCH 3/3] MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() Markos Chandras
2015-09-28 10:12 ` Markos Chandras
2015-09-28 13:15 ` kbuild test robot
2015-09-28 13:15 ` kbuild test robot
2015-10-12 10:24 ` [PATCH v2 " Markos Chandras
2015-10-12 10:24 ` Markos Chandras
2015-10-21 8:57 ` [PATCH v3 " Markos Chandras
2015-10-21 8:57 ` Markos Chandras
2015-10-23 1:41 ` Leonid Yegoshin [this message]
2015-10-23 1:41 ` [v3, " Leonid Yegoshin
2015-10-27 14:47 ` Ralf Baechle
2015-10-27 20:46 ` Leonid Yegoshin
2015-10-27 20:46 ` Leonid Yegoshin
2015-10-27 21:02 ` David Daney
2015-10-27 21:15 ` Leonid Yegoshin
2015-10-27 21:15 ` Leonid Yegoshin
2015-10-27 21:44 ` David Daney
2015-10-27 21:49 ` Leonid Yegoshin
2015-10-27 21:49 ` Leonid Yegoshin
2015-10-28 10:20 ` Alex Smith
2015-10-28 18:21 ` Leonid Yegoshin
2015-10-28 18:21 ` Leonid Yegoshin
2015-10-28 18:30 ` Alex Smith
2015-10-28 18:57 ` Leonid Yegoshin
2015-10-28 18:57 ` Leonid Yegoshin
2015-10-28 19:04 ` Alex Smith
2015-10-28 19:28 ` Leonid Yegoshin
2015-10-28 19:28 ` Leonid Yegoshin
2015-10-28 19:55 ` Alex Smith
2015-10-28 20:15 ` Leonid Yegoshin
2015-10-28 20:15 ` Leonid Yegoshin
2016-01-25 22:36 ` [PATCH v3 " Hauke Mehrtens
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