Hi Jim,
On 2/2/2015 5:11 PM, Jim Pennino wrote:
> Can one download an executable with these changes?
No, not yet. Like everything else in the development (aka v1.5) branch,
these changes are available only on a compile-it-yourself basis.
-- 73, Joe, K1JT
> --------------------------------------------
> On Mon, 2/2/15, Joe Taylor<j...@princeton.edu> wrote:
>
> Subject: [wsjt-devel] WSJT-X Decoder Performance
> To: wsjt-devel@lists.sourceforge.net
> Date: Monday, February 2, 2015, 11:45 AM
>
> Hi all,
>
> I have made further improvements to the speed of the
> decoders in WSJT-X,
> independently of any recourse to concurrent processing in
> machines with
> multiple CPUs. The changes involve
>
> 1. Making better choices for NFFT1 and NFFT2 (the lengths of
> forward and
> inverse FFTs in the JT9 downsampler.
>
> 2. Adjusting values of "limit" (the Fano timeout parameter)
> and "ccflim"
> (JT9 synchronizing threshold) under specified conditions.
>
> 3. Using "-O3" for the gfortran optimizer level.
>
> The following table presents measurements of decoding speed
> for a number
> of tests using WSJT-X versions 1.3, 1.4.0-rc2, 1.5r4925, and
> 1.5r4926.
> "Time" gives the time is seconds to decode the sample file
> 130610_2343.wav, which has 8 decodable JT9 signals and 9
> decodable JT65
> signals. "Decode" is the setting on the WSJT-X
> *Decode* menu. The
> column labeled "#" gives the number of decoded
> signals. (Note that
> selecting "Deepest" is required in order to decode one of
> the JT9
> signals.)
>
> These measurements were made on a Windows 7 machine with
> 4-core i5-2500 CPU.
>
> Program Version Time
> Decode #
> -------------------------------------------
> v1.3 r3673
> 2.48 s Deepest 17
> v1.4.0-rc2, r4400 2.28
> Deepest 17
> v1.5, r4925
> 1.01 Deepest 17
> v1.5, r4926
> 0.83 Deepest 17
> v1.5, r4926 -w 2 -m 2 0.80 Deepest
> 17
> v1.5, r4926
> 0.75 Normal 16
> v1.5, r4926
> 0.69 Fast 16
>
> The bottom line: At this stage, much has been gained by some
> careful
> algorithmic tuning. The decoder in r4926 is 3 times
> faster than the one
> in r3673, and 2.7 times faster than the one in r4400.
> In r4926 a small
> further improvement (about 4%) is obtained by using patience
> level "-w
> 2" and two threads ("-m 2") for the FFTs.
>
> Similar speed improvements were measured on a linux machine
> (Core 2 Duo,
> E6750 CPU).
>
> A further speed improvement around 10% should be obtainable
> by computing
> the JT65 symbol spectra (subroutine symspec65) on the fly,
> during the Rx
> minute, rather than as part of the end-of-minute *Decode*
> procedure.
> (This is already done for the JT9 symbol spectra.) My
> current view is
> that beyond that step, further speed improvement on
> single-core machines
> (or single-core processing on multi-core machines, as in all
> of the
> tabulated tests except one) will be difficult.
>
> Further improvements can probably be made by using more than
> one core
> concurrently, e.g., by using OpenMP. As I mentioned
> before, the biggest
> (or at least easiest) gain may come from running the JT9 and
> JT65
> decoders concurrently. It's hard to know whether the
> gains will be
> worthwhile, without trying. The programming effort may
> not be trivial.
>
> -- Joe, K1JT
>
>
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leadership blogs to news, videos, case studies, tutorials and more. Take a
look and join the conversation now. http://goparallel.sourceforge.net/
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