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There is currently no reliable way to measure RAM accesses with PAPI,
the previous way by counting load and store instructions is not very
useful, as it is unknown how many bytes are transferred in each
instruction.

On certain CPUs there is a reliable way to measure this via an "uncore"
performance counter, one can check if your CPU (and/or Linux kernel
version) support this by checking if the files

	/sys/devices/uncore_imc/events/data_reads
	/sys/devices/uncore_imc/events/data_writes

exist.

To access these counter from an unprivileged program one has to set the
"paranoia" level of the perf subsystem to at most 0, adjustable via the
file

	/proc/sys/kernel/perf_event_paranoid

Along with this change there is a small API/ABI breakage as some keyword
arguments related to the memory measurement have been renamed/split-up.

Additionally one can now also measure load and stores, and thus the
memory bandwidth. Therefore, also the arithmetic intensity.

One caveat, though: The user is responsible to provide a meaningful
value for the amount of bytes transferred in one load/store, via the
"bytes_per_ldsr" parameter of the new function %set_print_options.

Till now, I have now way of obtaining this value programmatically, and
it also can and will vary for different sections of a program.

For example, a SSE movapd instructions loads/stores 16 byte, but is
still counted as one "load and store" instruction, just as well as a
1-byte mov. Feel free to advise me on a better set of machine counters..

Also, somewhat updated documentation.

Now, one can select which kind of measurements are taken by calling the
member functions %measure_flops, and %measure_memory of a timer_t
object. For example

  type(timer_t) :: timer

  call timer%measure_flops(.true.)
  call timer%measure_memory(.true.)

  call timer%enable()

An explicit ftimings_init() call is now no longer necessary, PAPI will
be initialized on the first %measure_flops(.true.) call.

Next so some refactoring into four separate source files, support for
also recording values of perfomance counters via the PAPI library was
added, at the moment a FLOP count is measured and results are presented
in timer_print as MFlop/s.