Messages in this thread | | | Date | Thu, 31 Jan 2013 01:38:05 +0100 | Subject | Re: [PATCH 8/8] cputime: Safely read cputime of full dynticks CPUs | From | Frederic Weisbecker <> |
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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
> > 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.
Thanks.
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