Re: [patch] tracing/mm: add page frame snapshot trace

[Ingo Molnar <mingo@elte.hu>]

* Ingo Molnar <mingo@elte.hu> wrote:

> * Wu Fengguang <fengguang.wu@intel.com> wrote:
> 
> > 2) support concurrent object iterations
> >    For example, a huge 1TB memory space can be split up into 10
> >    segments which can be queried concurrently (with different options).
> 
> this should already be possible. If you lseek the trigger file, 
> that will be understood as an 'offset' by the patch, and then 
> write a (decimal) value into the file, that will be the count.
> 
> So it should already be possible to fork off nr_cpus helper 
> threads, one bound to each CPU, each triggering trace output of a 
> separate segment of the memory map - and each reading that CPU's 
> trace_pipe_raw file to recover the data - all in parallel.

And note that trace_pipe_raw supports splice(), while 
/proc/{kpageflags|kpagecount} does not, so the output side might 
probably be a bit faster than the /proc method.

	Ingo

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