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Message-ID: <20130125174247.GQ6395@linux.vnet.ibm.com> Date: Fri, 25 Jan 2013 09:42:47 -0800 From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com> To: Frederic Weisbecker <fweisbec@...il.com> Cc: LKML <linux-kernel@...r.kernel.org>, Andrew Morton <akpm@...ux-foundation.org>, Ingo Molnar <mingo@...nel.org>, Li Zhong <zhong@...ux.vnet.ibm.com>, Namhyung Kim <namhyung.kim@....com>, Paul Gortmaker <paul.gortmaker@...driver.com>, Peter Zijlstra <peterz@...radead.org>, Steven Rostedt <rostedt@...dmis.org>, Thomas Gleixner <tglx@...utronix.de>, Tony Luck <tony.luck@...el.com>, Fenghua Yu <fenghua.yu@...el.com> Subject: Re: [PATCH 0/7] cputime: Full dynticks task/cputime accounting v5 On Thu, Jan 17, 2013 at 02:24:28PM +0100, Frederic Weisbecker wrote: > Hi, > > This patchset was formerly called "Generic virtual based cputime accounting" > but I changed the name to better reflect what it's all about. > > This is the part of the full dynticks patchset that handles the task and CPU > time accounting without the tick. > > It's available at: > > git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git > vtime/generic-v5 > > There have been a lot of changes since latest full dynticks patchset: > > - Use sched_clock() instead of jiffies for better precision. And because > jiffies granularity was requiring too much dirty hacks to make it working. > (Thanks Steven for the suggestion). > > - To fully support sched_clock(), use a per nanosec granularity in cputime_t > > - Fix a deadlock with tsacct > > - Better description of the Kconfig > > - Don't scale generic vtime accounting against CFS precise task time accounting. > Now that we use sched_clock() we should have precise enough statistics. > > - Consolidate some code in the reader side > > - Make the reader irqsafe (fix potential deadlock against writers) > > > Most of the work is done. There are just a few small things I need to care about > to complete the full cputime support: > > * Also handle dynticks guest time accounting (p->gtime and p->utime). This > require to bring a new accessor: task_gtime() and to add guest_enter() and > guest_exit() on the context tracking subsystem. Then make the same treatment > than with utime and stime. No big deal. > > * New tasks start their cputime accounting from schedule() on sched-in time > (see arch_vtime_task_switch()). But I fear that idle tasks don't fall into this > category. That's a small detail but I hope I can find some generic way to handle it. > The boot init idle task is however handled. > > * Per nsec granularity requires that cputime_t directly maps to cputime64_t. This > is fine on 64 bits archs and mostly fine in 32 bits archs as well because readers > use seqlock to synchronize against writers. But reading struct kernel_cputstat > is not protected. Not sure yet how to solve that. > > So I'll likely focus on these items on the next version. Let's hope we can make > it ready for the next merge window. Queued for 3.9, thank you! Thanx, Paul > Thanks. > > --- > Frederic Weisbecker (7): > context_tracking: Export context state for generic vtime > cputime: Librarize per nsecs resolution cputime definitions > cputime: Move default nsecs_to_cputime() to jiffies based cputime file > cputime: Generic on-demand virtual cputime accounting > cputime: Allow dynamic switch between tick/virtual based cputime accounting > cputime: Use accessors to read task cputime stats > cputime: Safely read cputime of full dynticks CPUs > > > arch/alpha/kernel/osf_sys.c | 6 +- > arch/ia64/include/asm/cputime.h | 92 +---------- > arch/ia64/include/asm/thread_info.h | 4 +- > arch/ia64/include/asm/xen/minstate.h | 2 +- > arch/ia64/kernel/asm-offsets.c | 2 +- > arch/ia64/kernel/entry.S | 16 +- > arch/ia64/kernel/fsys.S | 4 +- > arch/ia64/kernel/head.S | 4 +- > arch/ia64/kernel/ivt.S | 8 +- > arch/ia64/kernel/minstate.h | 2 +- > arch/ia64/kernel/time.c | 4 +- > arch/powerpc/configs/chroma_defconfig | 2 +- > arch/powerpc/configs/corenet64_smp_defconfig | 2 +- > arch/powerpc/configs/pasemi_defconfig | 2 +- > arch/powerpc/include/asm/cputime.h | 6 +- > arch/powerpc/include/asm/lppaca.h | 2 +- > arch/powerpc/include/asm/ppc_asm.h | 4 +- > arch/powerpc/kernel/entry_64.S | 4 +- > arch/powerpc/kernel/time.c | 4 +- > arch/powerpc/platforms/pseries/dtl.c | 6 +- > arch/powerpc/platforms/pseries/setup.c | 6 +- > arch/s390/kernel/vtime.c | 6 +- > arch/x86/kernel/apm_32.c | 11 +- > drivers/isdn/mISDN/stack.c | 7 +- > fs/binfmt_elf.c | 8 +- > fs/binfmt_elf_fdpic.c | 7 +- > include/asm-generic/cputime.h | 66 +------- > include/asm-generic/cputime_jiffies.h | 72 +++++++++ > include/asm-generic/cputime_nsecs.h | 104 ++++++++++++ > include/linux/context_tracking.h | 28 ++++ > include/linux/hardirq.h | 4 +- > include/linux/init_task.h | 11 ++ > include/linux/kernel_stat.h | 2 +- > include/linux/sched.h | 34 ++++ > include/linux/tsacct_kern.h | 3 + > include/linux/vtime.h | 51 ++++-- > init/Kconfig | 23 +++- > kernel/acct.c | 6 +- > kernel/context_tracking.c | 22 +-- > kernel/cpu.c | 4 +- > kernel/delayacct.c | 7 +- > kernel/exit.c | 6 +- > kernel/fork.c | 14 ++ > kernel/posix-cpu-timers.c | 28 +++- > kernel/sched/cputime.c | 219 +++++++++++++++++++++++--- > kernel/signal.c | 12 +- > kernel/softirq.c | 6 +- > kernel/time/tick-sched.c | 5 +- > kernel/tsacct.c | 44 ++++-- > 49 files changed, 696 insertions(+), 296 deletions(-) > create mode 100644 include/asm-generic/cputime_jiffies.h > create mode 100644 include/asm-generic/cputime_nsecs.h > > -- > 1.7.5.4 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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