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The decrementer in Book E and 4xx processors interrupts on the
transition from 1 to 0, rather than on the 0 to -1 transition as on
64-bit server and 32-bit "classic" (6xx/7xx/7xxx) processors. At the
moment we subtract 1 from the count of how many decrementer ticks are
required before the next interrupt before putting it into the
decrementer, which is correct for server/classic processors, but could
possibly cause the interrupt to happen too early on Book E and 4xx if
the timebase/decrementer frequency is low.
This fixes the problem by making set_dec subtract 1 from the count for
server and classic processors, instead of having the callers subtract
1. Since set_dec already had a bunch of ifdefs to handle different
processor types, there is no net increase in ugliness. :)
Note that calling set_dec(0) may not generate an interrupt on some
processors. To make sure that decrementer_set_next_event always calls
set_dec with an interval of at least 1 tick, we set min_delta_ns of
the decrementer_clockevent to correspond to 2 ticks (2 rather than 1
to compensate for truncations in the conversions between ticks and
ns).
This also removes a redundant call to set the decrementer to
0x7fffffff - it was already set to that earlier in timer_interrupt.
Signed-off-by: Paul Mackerras <paulus@samba.org>
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This adds POWERPC specific hooks for scaled time accounting.
POWER6 includes a SPURR register. The SPURR is based off the PURR register
but is scaled based on CPU frequency and issue rates. This gives a more
accurate account of the instructions used per task. The PURR and timebase
will be constant relative to the wall clock, irrespective of the CPU
frequency.
This implementation reads the SPURR register in account_system_vtime which
is only call called on context witch and hard and soft irq entry and exit.
The percentage of user and system time is then estimated using the ratio of
these accounted by the PURR. If the SPURR is not present, the PURR read.
An earlier implementation of this patch read the SPURR whenever the PURR
was read, which included the system call entry and exit path.
Unfortunately this showed a performance regression on lmbench runs, so was
re-implemented.
I've included the lmbench results here when run bare metal on POWER6. 1st
column is the unpatch results. 2nd column is the results using the below
patch and the 3rd is the % diff of these results from the base. 4th and
5th columns are the results and % differnce from the base using the older
patch (SPURR read in syscall entry/exit path).
Base Scaled-Acct SPURR-in-syscall
Result Result % diff Result % diff
Simple syscall: 0.3086 0.3086 0.0000 0.3452 11.8600
Simple read: 0.4591 0.4671 1.7425 0.5044 9.86713
Simple write: 0.4364 0.4366 0.0458 0.4731 8.40971
Simple stat: 2.0055 2.0295 1.1967 2.0669 3.06158
Simple fstat: 0.5962 0.5876 -1.442 0.6368 6.80979
Simple open/close: 3.1283 3.1009 -0.875 3.2088 2.57328
Select on 10 fd's: 0.8554 0.8457 -1.133 0.8667 1.32101
Select on 100 fd's: 3.5292 3.6329 2.9383 3.6664 3.88756
Select on 250 fd's: 7.9097 8.1881 3.5197 8.2242 3.97613
Select on 500 fd's: 15.2659 15.836 3.7357 15.873 3.97814
Select on 10 tcp fd's: 0.9576 0.9416 -1.670 0.9752 1.83792
Select on 100 tcp fd's: 7.248 7.2254 -0.311 7.2685 0.28283
Select on 250 tcp fd's: 17.7742 17.707 -0.375 17.749 -0.1406
Select on 500 tcp fd's: 35.4258 35.25 -0.496 35.286 -0.3929
Signal handler installation: 0.6131 0.6075 -0.913 0.647 5.52927
Signal handler overhead: 2.0919 2.1078 0.7600 2.1831 4.35967
Protection fault: 0.7345 0.7478 1.8107 0.8031 9.33968
Pipe latency: 33.006 16.398 -50.31 33.475 1.42368
AF_UNIX sock stream latency: 14.5093 30.910 113.03 30.715 111.692
Process fork+exit: 219.8 222.8 1.3648 229.37 4.35623
Process fork+execve: 876.14 873.28 -0.32 868.66 -0.8533
Process fork+/bin/sh -c: 2830 2876.5 1.6431 2958 4.52296
File /var/tmp/XXX write bw: 1193497 1195536 0.1708 118657 -0.5799
Pagefaults on /var/tmp/XXX: 3.1272 3.2117 2.7020 3.2521 3.99398
Also, kernel compile times show no difference with this patch applied.
[pbadari@us.ibm.com: Avoid unnecessary PURR reading]
Signed-off-by: Michael Neuling <mikey@neuling.org>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Jay Lan <jlan@engr.sgi.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The clockevent bootup message only needs to be KERN_INFO.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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In testing the new clocksource and clockevent code on a PPC601
processor, I discovered that the clockevent multiplier value for the
decrementer clockevent was overflowing. Because the RTCL register in
the 601 effectively counts at 1GHz (it doesn't actually, but it
increases by 128 every 128ns), and the shift value was 32, that meant
the multiplier value had to be 2^32, which won't fit in an unsigned
long on 32-bit. The same problem would arise on any platform where
the timebase frequency was 1GHz or more (not that we actually have any
such machines today).
This fixes it by reducing the shift value to 16. Doing the
calculations with a resolution of 2^-16 nanoseconds (15 femtoseconds)
should be quite adequate. :)
Signed-off-by: Paul Mackerras <paulus@samba.org>
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On old powermacs, we sometimes set the decrementer to 1 in order to
trigger a decrementer interrupt, which we use to handle an interrupt
that was pending at the time when it was re-enabled. This was causing
the decrementer clock event device to call the event function for the
next event early, which was causing problems when high-res timers were
not enabled.
This fixes the problem by recording the timebase value at which the
next event should occur, and checking the current timebase against the
recorded value in timer_interrupt. If it isn't time for the next
event, it just reprograms the decrementer and returns.
This also subtracts 1 from the value stored into the decrementer,
which is appropriate because the decrementer interrupts on the
transition from 0 to -1, not when the decrementer reaches 0.
Signed-off-by: Paul Mackerras <paulus@samba.org>
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This registers a clock event structure for the decrementer and turns
on CONFIG_GENERIC_CLOCKEVENTS, which means that we now don't need
most of timer_interrupt(), since the work is done in generic code.
For secondary CPUs, their decrementer clockevent is registered when
the CPU comes up (the generic code automatically removes the
clockevent when the CPU goes down).
Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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With these functions implemented we cooperate better with the generic
timekeeping code. This obsoletes the need for the timer sysdev as a bonus.
Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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Recent changes to the timekeeping code broke support for the PowerPC 601
processor which doesn't have the usual timebase facility but a slightly
different thing called (yuck) the RTC.
This fixes it, boot tested on an old 601 based PowerMac 7200.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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Allow generic_calibrate_decr to work for 40x platforms. Given that the hardware
behavior is identical, this also changes the set_dec function to reload the PIT
on 40x to match the behavior 44x currently has.
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
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This removes several duplicate includes from arch/powerpc/.
Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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From: Maynard Johnson <mpjohn@us.ibm.com>
This patch updates the existing arch/powerpc/oprofile/op_model_cell.c
to add in the SPU profiling capabilities. In addition, a 'cell' subdirectory
was added to arch/powerpc/oprofile to hold Cell-specific SPU profiling code.
Exports spu_set_profile_private_kref and spu_get_profile_private_kref which
are used by OProfile to store private profile information in spufs data
structures.
Also incorporated several fixes from other patches (rrn). Check pointer
returned from kzalloc. Eliminated unnecessary cast. Better error
handling and cleanup in the related area. 64-bit unsigned long parameter
was being demoted to 32-bit unsigned int and eventually promoted back to
unsigned long.
Signed-off-by: Carl Love <carll@us.ibm.com>
Signed-off-by: Maynard Johnson <mpjohn@us.ibm.com>
Signed-off-by: Bob Nelson <rrnelson@us.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Acked-by: Paul Mackerras <paulus@samba.org>
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When booting a current kernel with CONFIG_PRINTK_TIME enabled you'll
see messages like:
[ 0.000000] time_init: decrementer frequency = 188.044000 MHz
[ 0.000000] time_init: processor frequency = 1504.352000 MHz
[3712914.436297] Console: colour dummy device 80x25
This cause by the initialisation of tb_to_ns_scale in time_init(), suddenly the
multiplication in sched_clock() now does something :). This patch modifies
sched_clock() to report the offset since the machine booted so the same
printk's now look like:
[ 0.000000] time_init: decrementer frequency = 188.044000 MHz
[ 0.000000] time_init: processor frequency = 1504.352000 MHz
[ 0.000135] Console: colour dummy device 80x25
Effectivly including the uptime in printk()s.
This patch makes tb_to_ns_scale and tb_to_ns_shift static and
read_mostly for good measure.
Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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Currently iSeries will recalibrate the cputime_factors in the first
settimeofday() call.
It seems the reason for doing this is to ensure a resaonable time delta after
time_init(). On current kernels (with udev), this call is made 40-60 seconds
into the boot process, by moving it to a late initcall it is called
approximately 5 seconds after time_init() is called. This is sufficient to
recalibrate the timebase.
Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
CC: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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For POWERPC, stolen time accounts for cycles lost to the hypervisor or
PURR cycles attributed to the other SMT thread. Hence, when a PURR is
available, we should still calculate stolen time, irrespective of being
virtualised.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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cpu_purr_data is a per-cpu array used to account for stolen time on
partitioned systems. It used to be the case that cpus accessed each
others' cpu_purr_data, so each entry was protected by a spinlock.
However, the code was reworked ("Simplify stolen time calculation")
with the result that each cpu accesses its own cpu_purr_data and not
those of other cpus. This means we can get rid of the spinlock as
long as we're careful to disable interrupts when accessing
cpu_purr_data in process context.
Signed-off-by: Nathan Lynch <ntl@pobox.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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Greatly simplify the function smp_space_timers.
The stolen time calculation (per comment within the code) doesn't need the
half-jiffy stagger any more. There isn't an issue with bouncing off global
locks, so we really shouldn't need any sort of staggering at all.
However, the last_jiffy value still needs to be set. This removes the
extra stagger logic, and just sets the values.
This change should benefit applications that rely on barrier
synchronization, and will help cut down OS jitter.
Boot tested across the board (G5,power3,power4,power5,970mp blade).
Signed-off-by: Will Schmidt <will_schmidt@vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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This reverts commit 7a69af63e788a324d162201a0b23df41bcf158dd.
As advised by David Brownell:
http://marc.theaimsgroup.com/?l=linux-kernel&m=116387226902131&w=2
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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In calculating stolen time, we were trying to actually account for time
spent in the hypervisor. We don't really have enough information to do
that accurately, so don't try. Instead, we now calculate stolen time as
time that the current cpu thread is not actually dispatching instructions.
On chips without a PURR, we cannot do this, so stolen time will always
be zero. On chips with a PURR, this is merely the difference between
the elapsed PURR values and the elapsed TB values.
This gives us much more sane vaules from tools such as mpstat, even if
they are still a bit strange e.g. 2 busy threads on one cpu will both
appear to have 50% user time and 50% stolen time while 1 busy thread on
a cpu will look like 100% user on one of them and 100% idle on the other.
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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Remove struct pt_regs * from all handlers.
Also remove the regs argument from get_irq() functions.
Compile tested with arch/powerpc/config/* and
arch/ppc/configs/prep_defconfig
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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Maintain a per-CPU global "struct pt_regs *" variable which can be used instead
of passing regs around manually through all ~1800 interrupt handlers in the
Linux kernel.
The regs pointer is used in few places, but it potentially costs both stack
space and code to pass it around. On the FRV arch, removing the regs parameter
from all the genirq function results in a 20% speed up of the IRQ exit path
(ie: from leaving timer_interrupt() to leaving do_IRQ()).
Where appropriate, an arch may override the generic storage facility and do
something different with the variable. On FRV, for instance, the address is
maintained in GR28 at all times inside the kernel as part of general exception
handling.
Having looked over the code, it appears that the parameter may be handed down
through up to twenty or so layers of functions. Consider a USB character
device attached to a USB hub, attached to a USB controller that posts its
interrupts through a cascaded auxiliary interrupt controller. A character
device driver may want to pass regs to the sysrq handler through the input
layer which adds another few layers of parameter passing.
I've build this code with allyesconfig for x86_64 and i386. I've runtested the
main part of the code on FRV and i386, though I can't test most of the drivers.
I've also done partial conversion for powerpc and MIPS - these at least compile
with minimal configurations.
This will affect all archs. Mostly the changes should be relatively easy.
Take do_IRQ(), store the regs pointer at the beginning, saving the old one:
struct pt_regs *old_regs = set_irq_regs(regs);
And put the old one back at the end:
set_irq_regs(old_regs);
Don't pass regs through to generic_handle_irq() or __do_IRQ().
In timer_interrupt(), this sort of change will be necessary:
- update_process_times(user_mode(regs));
- profile_tick(CPU_PROFILING, regs);
+ update_process_times(user_mode(get_irq_regs()));
+ profile_tick(CPU_PROFILING);
I'd like to move update_process_times()'s use of get_irq_regs() into itself,
except that i386, alone of the archs, uses something other than user_mode().
Some notes on the interrupt handling in the drivers:
(*) input_dev() is now gone entirely. The regs pointer is no longer stored in
the input_dev struct.
(*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does
something different depending on whether it's been supplied with a regs
pointer or not.
(*) Various IRQ handler function pointers have been moved to type
irq_handler_t.
Signed-Off-By: David Howells <dhowells@redhat.com>
(cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
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* git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc: (29 commits)
[POWERPC] Fix rheap alignment problem
[POWERPC] Use check_legacy_ioport() for ISAPnP
[POWERPC] Avoid NULL pointer in gpio1_interrupt
[POWERPC] Enable generic rtc hook for the MPC8349 mITX
[POWERPC] Add powerpc get/set_rtc_time interface to new generic rtc class
[POWERPC] Create a "wrapper" script and use it in arch/powerpc/boot
[POWERPC] fix spin lock nesting in hvc_iseries
[POWERPC] EEH failure to mark pci slot as frozen.
[POWERPC] update powerpc defconfig files after libata kconfig breakage
[POWERPC] enable sysrq in pmac32_defconfig
[POWERPC] UPIO_TSI cleanup
[POWERPC] rewrite mkprep and mkbugboot in sane C
[POWERPC] maple/pci iomem annotations
[POWERPC] powerpc oprofile __user annotations
[POWERPC] cell spufs iomem annotations
[POWERPC] NULL noise removal: spufs
[POWERPC] ppc math-emu needs -fno-builtin-fabs for math.c and fabs.c
[POWERPC] update mpc8349_itx_defconfig and remove some debug settings
[POWERPC] Always call cede in pseries dedicated idle loop
[POWERPC] Fix loop logic in irq_alloc_virt()
...
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Add powerpc get/set_rtc_time interface to new generic rtc class. This
abstracts rtc chip specific code from the platform code for rtc-over-i2c
platforms. Specific RTC chip support is now configured under
Device Drivers -> Real Time Clock. Setting time of day from the RTC
on startup is also configurable.
this time without the potentially platform breaking initcall.
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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With 2.6.18-rc4-mm2, now wall_jiffies will always be the same as jiffies.
So we can kill wall_jiffies completely.
This is just a cleanup and logically should not change any real behavior
except for one thing: RTC updating code in (old) ppc and xtensa use a
condition "jiffies - wall_jiffies == 1". This condition is never met so I
suppose it is just a bug. I just remove that condition only instead of
kill the whole "if" block.
[heiko.carstens@de.ibm.com: s390 build fix and cleanup]
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: Andi Kleen <ak@muc.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ian Molton <spyro@f2s.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Hirokazu Takata <takata.hirokazu@renesas.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Kazumoto Kojima <kkojima@rr.iij4u.or.jp>
Cc: Richard Curnow <rc@rc0.org.uk>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Miles Bader <uclinux-v850@lsi.nec.co.jp>
Cc: Chris Zankel <chris@zankel.net>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Pass ticks to do_timer() and update_times(), and adjust x86_64 and s390
timer interrupt handler with this change.
Currently update_times() calculates ticks by "jiffies - wall_jiffies", but
callers of do_timer() should know how many ticks to update. Passing ticks
get rid of this redundant calculation. Also there are another redundancy
pointed out by Martin Schwidefsky.
This cleanup make a barrier added by
5aee405c662ca644980c184774277fc6d0769a84 needless. So this patch removes
it.
As a bonus, this cleanup make wall_jiffies can be removed easily, since now
wall_jiffies is always synced with jiffies. (This patch does not really
remove wall_jiffies. It would be another cleanup patch)
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Acked-by: Russell King <rmk@arm.linux.org.uk>
Cc: Ian Molton <spyro@f2s.com>
Cc: Mikael Starvik <starvik@axis.com>
Acked-by: David Howells <dhowells@redhat.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Hirokazu Takata <takata.hirokazu@renesas.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Kazumoto Kojima <kkojima@rr.iij4u.or.jp>
Cc: Richard Curnow <rc@rc0.org.uk>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Miles Bader <uclinux-v850@lsi.nec.co.jp>
Cc: Chris Zankel <chris@zankel.net>
Acked-by: "Luck, Tony" <tony.luck@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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There are various places where we want to extract an unsigned long
value from a device-tree property that can be 1 or 2 cells in length.
This replaces some open-coded calculations, and one place where we
assumed without checking that properties were the length we wanted,
with a little of_read_ulong() helper.
Signed-off-by: Paul Mackerras <paulus@samba.org>
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This fixes a hang on ppc32.
The problem was that I was comparing a 32-bit quantity with a 64-bit
quantity, and consequently time wasn't advancing. This makes us use a
64-bit quantity on all platforms, which ends up simplifying the code
since we can now get rid of the tb_last_stamp variable (which actually
fixes another bug that Ben H and I noticed while going carefully through
the code).
This works fine on my G4 tibook. Let me know how it goes on your
machines.
Acked-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Mikael Pettersson <mikpe@it.uu.se>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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There are two problems in the powerpc gettimeofday code which can
cause incorrect results to be returned.
The first is that there is a race between do_gettimeofday and the
timer interrupt:
1. do_gettimeofday does get_tb()
2. decrementer exception on boot cpu which runs timer_recalc_offset,
which also samples the timebase and updates the do_gtod structure
with a greater timebase value.
3. do_gettimeofday calls __do_gettimeofday, which leads to the
negative result from tb_val - temp_varp->tb_orig_stamp.
The second is caused by taking the boot cpu offline, which can cause
the value of tb_last_jiffy to be increased past the currently
available timebase, causing the same underflow as above.
[paulus@samba.org - define and use data_barrier() instead of mb().]
Signed-off-by: Nathan Lynch <ntl@pobox.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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Now that get_property() returns a void *, there's no need to cast its
return value. Also, treat the return value as const, so we can
constify get_property later.
powerpc core changes.
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
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This fixes the clock source updates in update_wall_time() to correctly
track the time coming in via current_tick_length(). Optimize the fast
paths to be as short as possible to keep the overhead low.
Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Acked-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Change the current_tick_length() function so it takes an argument which
specifies how much precision to return in shifted nanoseconds. This provides
a simple way to convert between NTPs internal nanoseconds shifted by
(SHIFT_SCALE - 10) to other shifted nanosecond units that are used by the
clocksource abstraction.
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Support the ibm,extended-*-frequency properties found in recent POWER5
firmware:
cpus/PowerPC,POWER5@0/clock-frequency
59aa5880 (1504336000)
cpus/PowerPC,POWER5@0/ibm,extended-clock-frequency
00000000 59aa5880
cpus/PowerPC,POWER5@0/timebase-frequency
0b354b10 (188042000)
cpus/PowerPC,POWER5@0/ibm,extended-timebase-frequency
00000000 0b354b10
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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Not even the iSeries maintainer seems to have access to this legendary
piranha simulator. It adds a bit of ugliness in the common time init
code, and if it's no longer used we might as well be done with it and
remove the bloat.
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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Move time_init console output to KERN_DEBUG prink level. No need to
print it at every boot.
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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for_each_cpu() actually iterates across all possible CPUs. We've had mistakes
in the past where people were using for_each_cpu() where they should have been
iterating across only online or present CPUs. This is inefficient and
possibly buggy.
We're renaming for_each_cpu() to for_each_possible_cpu() to avoid this in the
future.
This patch replaces for_each_cpu with for_each_possible_cpu.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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The recent changes to keep gettimeofday in sync with xtime had the side
effect that it was occasionally possible for the time reported by
gettimeofday to go back by a microsecond. There were two reasons:
(1) when we recalculated the offsets used by gettimeofday every 2^31
timebase ticks, we lost an accumulated fractional microsecond, and
(2) because the update is done some time after the notional start of
jiffy, if ntp is slowing the clock, it is possible to see time go backwards
when the timebase factor gets reduced.
This fixes it by (a) slowing the gettimeofday clock by about 1us in
2^31 timebase ticks (a factor of less than 1 in 3.7 million), and (b)
adjusting the timebase offsets in the rare case that the gettimeofday
result could possibly go backwards (i.e. when ntp is slowing the clock
and the timer interrupt is late). In this case the adjustment will
reduce to zero eventually because of (a).
Signed-off-by: Paul Mackerras <paulus@samba.org>
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The inline cputime_to_foo and foo_to_cputime conversion functions in
include/asm-powerpc/cputime.h refer to 5 variables, which need to be
exported if those functions are to be usable from modules.
Signed-off-by: Paul Mackerras <paulus@samba.org>
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This implements accurate task and cpu time accounting for 64-bit
powerpc kernels. Instead of accounting a whole jiffy of time to a
task on a timer interrupt because that task happened to be running at
the time, we now account time in units of timebase ticks according to
the actual time spent by the task in user mode and kernel mode. We
also count the time spent processing hardware and software interrupts
accurately. This is conditional on CONFIG_VIRT_CPU_ACCOUNTING. If
that is not set, we do tick-based approximate accounting as before.
To get this accurate information, we read either the PURR (processor
utilization of resources register) on POWER5 machines, or the timebase
on other machines on
* each entry to the kernel from usermode
* each exit to usermode
* transitions between process context, hard irq context and soft irq
context in kernel mode
* context switches.
On POWER5 systems with shared-processor logical partitioning we also
read both the PURR and the timebase at each timer interrupt and
context switch in order to determine how much time has been taken by
the hypervisor to run other partitions ("steal" time). Unfortunately,
since we need values of the PURR on both threads at the same time to
accurately calculate the steal time, and since we can only calculate
steal time on a per-core basis, the apportioning of the steal time
between idle time (time which we ceded to the hypervisor in the idle
loop) and actual stolen time is somewhat approximate at the moment.
This is all based quite heavily on what s390 does, and it uses the
generic interfaces that were added by the s390 developers,
i.e. account_system_time(), account_user_time(), etc.
This patch doesn't add any new interfaces between the kernel and
userspace, and doesn't change the units in which time is reported to
userspace by things such as /proc/stat, /proc/<pid>/stat, getrusage(),
times(), etc. Internally the various task and cpu times are stored in
timebase units, but they are converted to USER_HZ units (1/100th of a
second) when reported to userspace. Some precision is therefore lost
but there should not be any accumulating error, since the internal
accumulation is at full precision.
Signed-off-by: Paul Mackerras <paulus@samba.org>
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This fixes a regression which was introduced by moving ppc32 to use
the same sort of lockless gettimeofday as ppc64 has been using for
some time. This involves getting the timebase and performing some
simple arithmetic to convert it to seconds and microseconds. However,
the factor and offset used there weren't being updated when NTP
varied the tick length using adjtimex. 64-bit didn't notice the
problem because it had a hook in the 32-bit adjtimex compat routine
that attempted to work out what the generic timekeeping code would
do and alter the factor and offset to match. However, that code
was very complex and it wasn't clear that it still matched what the
generic code would do.
Now we use the generic current_tick_length() routine that was recently
added to check that the current tick will be as long as we expect; if
not we recompute the factor and offset. This keeps gettimeofday and
xtime in sync. In addition we check that gettimeofday hasn't got ahead
of xtime on each timer interrupt; if it has, we resync.
Signed-off-by: Paul Mackerras <paulus@samba.org>
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remove pointer/integer confusion
Signed-off-by: Olaf Hering <olh@suse.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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At present the lppaca - the structure shared with the iSeries
hypervisor and phyp - is contained within the PACA, our own low-level
per-cpu structure. This doesn't have to be so, the patch below
removes it, making a separate array of lppaca structures.
This saves approximately 500*NR_CPUS bytes of image size and kernel
memory, because we don't need aligning gap between the Linux and
hypervisor portions of every PACA. On the other hand it means an
extra level of dereference in many accesses to the lppaca.
The patch also gets rid of several places where we assign the paca
address to a local variable for no particular reason.
Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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This patch removes several unnecessary fields from the paca:
- next_jiffy_update_tb was simply unused. Remove trivially.
- The exdsi exception save area was not used. There were plans to use
it, but they never seem to have gone anywhere. If they ever do, we
can put it back. Remove from the paca, and from asm-offsets.c
- The default_decr field was used from asm, but was only ever assigned
the value of tb_ticks_per_jiffy. Just access tb_ticks_per_jiffy from
asm directly instead.
Built and booted on POWER5 LPAR and iSeries RS64.
Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
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My earlier merge of delay.h introduced a timebase-based udelay for
32-bit machines but also broke the 601, which doesn't have the
timebase register. This fixes it by using the 601's RTC register on
the 601, and also moves __delay() and udelay() to be out-of-line in
arch/powerpc/kernel/time.c. These functions aren't really performance
critical, after all.
Signed-off-by: Paul Mackerras <paulus@samba.org>
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Paul Mackerras
Michael Neuling
Anton Blanchard
Tony Breeds
Benjamin Herrenschmidt
Josh Boyer
Jesper Juhl
Bob Nelson
Nathan Lynch
will schmidt
Stephen Rothwell
Kim Phillips
Olaf Hering
David Howells
Linus Torvalds
Atsushi Nemoto
Jeremy Kerr
Jörn Engel
Roman Zippel
john stultz
Olof Johansson
KAMEZAWA Hiroyuki
Olaf Hering
David Gibson