Messages in this thread | | | Date | Fri, 1 May 2015 18:45:26 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 3/3] context_tracking,x86: remove extraneous irq disable & enable from context tracking on syscall entry |
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* Rik van Riel <riel@redhat.com> wrote:
> On 05/01/2015 12:37 PM, Ingo Molnar wrote: > > > Also note that this bit in context_tracking_enter(): > > > > if (state == CONTEXT_USER) { > > trace_user_enter(0); > > vtime_user_enter(current); > > } > > > > > > is related to precise time measurement of user/kernel execution > > times, it's not needed by the scheduler at all, it's just exported > > to tooling. It's not fundamental to the scheduler. > > Any objections to the idea from the other thread to simply keep the > time accumulating in buffers in local_clock() units, and only update > the task vtime once a second or so?
So I really think per syscall overhead is the wrong thing to do for anything that a common distro enables.
I see very little use for such precise, high-freq measurements on normal systems - and abnormal systems could enable it dynamically just like they can enable syscall auditing.
I.e. I don't mind the occasional crazy piece of code, as long as it does not hurt the innocent.
Thanks,
Ingo
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