Messages in this thread | | | Date | Thu, 31 Jan 2013 08:24:22 +0100 | Subject | Re: [PATCH 8/8] cputime: Safely read cputime of full dynticks CPUs | From | Sedat Dilek <> |
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On Thu, Jan 31, 2013 at 1:38 AM, Frederic Weisbecker <fweisbec@gmail.com> wrote: > 2013/1/28 Sedat Dilek <sedat.dilek@gmail.com>: >> On Mon, Jan 28, 2013 at 8:04 PM, Frederic Weisbecker <fweisbec@gmail.com> wrote: >>> While remotely reading the cputime of a task running in a >>> full dynticks CPU, the values stored in utime/stime fields >>> of struct task_struct may be stale. Its values may be those >>> of the last kernel <-> user transition time snapshot and >>> we need to add the tickless time spent since this snapshot. >>> >>> To fix this, flush the cputime of the dynticks CPUs on >>> kernel <-> user transition and record the time / context >>> where we did this. Then on top of this snapshot and the current >>> time, perform the fixup on the reader side from task_times() >>> accessors. >>> >>> 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> >>> [fixed kvm module related build errors] >>> Signed-off-by: Sedat Dilek <sedat.dilek@gmail.com> >>> >> >> Can you explain a bit what is the difference between "3.8-rc4-nohz3" >> and "full-dynticks-cputime-for-mingo" patchsets? > > 3.8-rc4-nohz3 is the latest experimental tree that implements full > dynticks. It includes an earlier version of full dynticks cputime and > many other things to make the full dynticks possible: nohz printk, > many tweaks on the scheduler and timers...etc >
So, dynticks-cputime will go into 3.9? What about the other parts? Coming later?
>> >> Does the latter need no more EXPORT_SYMBOL_GPL for vtime_guest_enter() >> and vtime_guest_exit() when CONFIG_KVM=m (see [1])? > > It doesn't need export symbol on vtime_guest_() APIs, only on > guest_enter and guest_exit. >
I verified this by building by myself.
- Sedat -
> Thanks.
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