[darcs-users] darcs patch: switch Darcs.Patch.FileName to be ByteString.Char8 int...

Jason Dagit dagit at codersbase.com
Thu Sep 24 03:34:13 UTC 2009


On Wed, Sep 23, 2009 at 7:50 PM, Jason Dagit <dagit at codersbase.com> wrote:

>
> PS I'll try to reply to this with data to quantify the
> performance gains.
>

Here we go.

I've compiled an unmodified profiling-enabled version of darcs in my path as
darcs-prof-base.

darcs-prof-base says during a test run:
500 MB total memory in use (4 MB lost due to fragmentation)
499 MB total memory in use (4 MB lost due to fragmentation)

Productivity  33.6% of total user, 29.5% of total elapsed
Productivity  30.4% of total user, 25.6% of total elapsed

After my patch darcs says this:
516 MB total memory in use (4 MB lost due to fragmentation)
515 MB total memory in use (4 MB lost due to fragmentation)

Productivity  52.4% of total user, 36.3% of total elapsed
Productivity  52.4% of total user, 36.3% of total elapsed

The in-ram memory usage has increased about 15 megs.  This is unfortunate,
but from that we gain about 20% productivity.

Attached are pdfs showing how the heap usage has changed.  Notice that the
amount of heap consumed by lists goes way down and is replaced by an overall
smaller usage of ByteString.  I think the profiling data really speaks to
this as being quite an improvement over the existing code, assuming we can
work out the details of the encode/decode with respect to UTF-8.

Please let me know if you have questions!

Thanks,
Jason
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