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path: root/include/asm-generic/cputime_nsecs.h
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2013-04-26cputime_nsecs: use math64.h for nsec resolution conversion helpersKevin Hilman
For the nsec resolution conversions to be useable on non 64-bit architectures, the helpers in <linux/math64.h> need to be used so the right arch-specific 64-bit math helpers can be used (e.g. do_div()) Signed-off-by: Kevin Hilman <khilman@linaro.org> Cc: Christoph Lameter <cl@linux.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2013-02-24cputime: Constify timeval_to_cputime(timeval) argumentLi Zhong
Saw the following compiler warning on the linux-next tree: kernel/itimer.c: In function 'set_cpu_itimer': kernel/itimer.c:152:2: warning: passing argument 1 of 'timeval_to_cputime' discards 'const' qualifier from pointer target type [enabled by default] ... timeval_to_cputime() is always passed a constant timeval in argument, we need to teach the nsecs based cputime implementation about that. Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Kevin Hilman <khilman@linaro.org> Link: http://lkml.kernel.org/r/1361636925-22288-2-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Kevin Hilman <khilman@linaro.org>
2013-01-27cputime: Generic on-demand virtual cputime accountingFrederic Weisbecker
If we want to stop the tick further idle, we need to be able to account the cputime without using the tick. Virtual based cputime accounting solves that problem by hooking into kernel/user boundaries. However implementing CONFIG_VIRT_CPU_ACCOUNTING require low level hooks and involves more overhead. But we already have a generic context tracking subsystem that is required for RCU needs by archs which plan to shut down the tick outside idle. This patch implements a generic virtual based cputime accounting that relies on these generic kernel/user hooks. There are some upsides of doing this: - This requires no arch code to implement CONFIG_VIRT_CPU_ACCOUNTING if context tracking is already built (already necessary for RCU in full tickless mode). - We can rely on the generic context tracking subsystem to dynamically (de)activate the hooks, so that we can switch anytime between virtual and tick based accounting. This way we don't have the overhead of the virtual accounting when the tick is running periodically. And one downside: - There is probably more overhead than a native virtual based cputime accounting. But this relies on hooks that are already set anyway. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2013-01-27cputime: Librarize per nsecs resolution cputime definitionsFrederic Weisbecker
The full dynticks cputime accounting that we'll soon introduce will rely on sched_clock(). And its clock can have a per nanosecond granularity. To prepare for this, we need to have a cputime_t implementation that has this precision. ia64 virtual cputime accounting already uses that granularity so all we need is to librarize its implementation in the asm generic headers. Also librarize the default per jiffy granularity cputime_t as well so that we can easily pick either implementation depending on the cputime accounting config we choose. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com>