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authorFrederic Weisbecker <fweisbec@gmail.com>2012-07-25 01:56:04 -0400
committerFrederic Weisbecker <fweisbec@gmail.com>2013-01-27 13:23:27 -0500
commitabf917cd91cbb73952758f9741e2fa65002a48ee (patch)
tree5f975b87615dcaed9c98bc74b4548d568b92dcbc /init
parentae8dda5c473bf1a85913942adcaac449e5754bf3 (diff)
cputime: Generic on-demand virtual cputime accounting
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>
Diffstat (limited to 'init')
-rw-r--r--init/Kconfig23
1 files changed, 22 insertions, 1 deletions
diff --git a/init/Kconfig b/init/Kconfig
index be8b7f55312d..a05f843e7e52 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -326,6 +326,9 @@ source "kernel/time/Kconfig"
326 326
327menu "CPU/Task time and stats accounting" 327menu "CPU/Task time and stats accounting"
328 328
329config VIRT_CPU_ACCOUNTING
330 bool
331
329choice 332choice
330 prompt "Cputime accounting" 333 prompt "Cputime accounting"
331 default TICK_CPU_ACCOUNTING if !PPC64 334 default TICK_CPU_ACCOUNTING if !PPC64
@@ -342,9 +345,10 @@ config TICK_CPU_ACCOUNTING
342 345
343 If unsure, say Y. 346 If unsure, say Y.
344 347
345config VIRT_CPU_ACCOUNTING 348config VIRT_CPU_ACCOUNTING_NATIVE
346 bool "Deterministic task and CPU time accounting" 349 bool "Deterministic task and CPU time accounting"
347 depends on HAVE_VIRT_CPU_ACCOUNTING 350 depends on HAVE_VIRT_CPU_ACCOUNTING
351 select VIRT_CPU_ACCOUNTING
348 help 352 help
349 Select this option to enable more accurate task and CPU time 353 Select this option to enable more accurate task and CPU time
350 accounting. This is done by reading a CPU counter on each 354 accounting. This is done by reading a CPU counter on each
@@ -354,6 +358,23 @@ config VIRT_CPU_ACCOUNTING
354 this also enables accounting of stolen time on logically-partitioned 358 this also enables accounting of stolen time on logically-partitioned
355 systems. 359 systems.
356 360
361config VIRT_CPU_ACCOUNTING_GEN
362 bool "Full dynticks CPU time accounting"
363 depends on HAVE_CONTEXT_TRACKING && 64BIT
364 select VIRT_CPU_ACCOUNTING
365 select CONTEXT_TRACKING
366 help
367 Select this option to enable task and CPU time accounting on full
368 dynticks systems. This accounting is implemented by watching every
369 kernel-user boundaries using the context tracking subsystem.
370 The accounting is thus performed at the expense of some significant
371 overhead.
372
373 For now this is only useful if you are working on the full
374 dynticks subsystem development.
375
376 If unsure, say N.
377
357config IRQ_TIME_ACCOUNTING 378config IRQ_TIME_ACCOUNTING
358 bool "Fine granularity task level IRQ time accounting" 379 bool "Fine granularity task level IRQ time accounting"
359 depends on HAVE_IRQ_TIME_ACCOUNTING 380 depends on HAVE_IRQ_TIME_ACCOUNTING