Messages in this thread | | | Date | Fri, 15 Jun 2012 14:13:25 +0200 | From | Ingo Molnar <> | Subject | Re: [RFC GIT PULL] nohz: Basic cputime accounting for adaptive tickless |
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* Frederic Weisbecker <fweisbec@gmail.com> wrote:
> On Thu, Jun 14, 2012 at 04:36:33PM +0200, Ingo Molnar wrote: > > > > * Frederic Weisbecker <fweisbec@gmail.com> wrote: > > > > > > > > > > I'll try something with that. > > > > > > > > > > > > > > Maybe sanitize all the variants under a single set of > > > > > > > wrappers/callbacks? > > > > > > > > > > > > Yes, please! > > > > > > > > > > Sure, I'm working in it. > > > > > > > > Please keep me in the loop, I want to avoid that things > > > > break on s390. Thanks. > > > > > > Well, I realize I can't consolidate much between ia64, s390 > > > and ppc because they all handle virtual cpu time accounting > > > very differently. I'm also not what the virtual timer is for. > > > > As a first step I'd suggest to create a superset of all existing > > and relied-upon wrappers/callbacks, into a single obvious > > sched_*() or time_*() namespace, without breaking functionality. > > But the API is already well defined. The arch just need to > implement account_system_vtime() and account_process_tick() > and record the time on the kernel boundaries. This is pretty > well contained in ppc entry.S where it is implemented through > ACCOUNT_CPU_USER_ENTRY/EXIT macros (although I see the time > accounted on syscall boundaries but not in exceptions), it's > more complicated in ia64 as the virt accounting is spread here > and there in entry.S and it's always on in s390. > > May be we could standardize a bit the way we save and account > the time. This require some non-trivial asm surgery on archs I > don't know much about though.
Yeah, account_*() is a fine API too - as long as it's a unification of all time accounting functionality.
Thanks,
Ingo
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