* Mike Galbraith <umgwanakikbuti@xxxxxxxxx> wrote: > On Thu, 2016-02-25 at 09:14 +0100, Ingo Molnar wrote: > > > But but ... 'context tracking' is not really something that a regular distro > > kernel cares about much - it's a nohz-full special AFAICS. Let me qualify that: with the timer code maintenance hat on I really love all nohz variants (the deeper the better), but now I have my x86 maintainer hat on, and as such I'm really annoyed at those nohz folks adding overhead to the syscall hot path! ;-) > (psst.. distros are shipping it) Yeah, indeed, Fedora does - but AFAICS: fomalhaut:~> grep NO_HZ /boot/config-4.1.13-100.fc21.x86_64 CONFIG_NO_HZ_COMMON=y # CONFIG_NO_HZ_IDLE is not set CONFIG_NO_HZ_FULL=y # CONFIG_NO_HZ_FULL_ALL is not set # CONFIG_NO_HZ_FULL_SYSIDLE is not set CONFIG_NO_HZ=y CONFIG_RCU_FAST_NO_HZ=y ... which won't result in actual full-nohz CPUs unless you boot it with a special boot parameter, right? What is the easiest way to query which/how many CPUs are in nohz-full mode and do context tracking? I somehow thought /proc/timer_* had that info, but that does not appear to be the case. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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