[ANNOUNCEMENT] Updated: setup.exe (Release 2.871)

[ANNOUNCEMENT] Updated: setup.exe (Release 2.871)

[Corinna Vinschen]

Hi folks,

A new version of Setup, release 2.871, has been uploaded to

  https://cygwin.com/setup-x86.exe     (32 bit version)
  https://cygwin.com/setup-x86_64.exe  (64 bit version)

Changes compared to 2.870:

- Improved performance in terms of SHA512 checksum computation.

- Add a "Retry" button to the "File in use" dialog.

- Avoid truncation of "Bin?" and "Src? columns in package chooser.

- Various under-the-hood optimizations of log output.


Please send bug reports, as usual, to the public mailing list
cygwin AT cygwin DOT com.


Have fun,
Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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Re: [ANNOUNCEMENT] Updated: setup.exe (Release 2.871)

[Steven Penny]

On Fri, May 29, 2015 at 8:51 AM, Corinna Vinschen wrote:
> - Improved performance in terms of SHA512 checksum computation.

Thanks for this, but how was it done?

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Re: [ANNOUNCEMENT] Updated: setup.exe (Release 2.871)

[Corinna Vinschen]

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On May 29 17:49, Steven Penny wrote:
> On Fri, May 29, 2015 at 8:51 AM, Corinna Vinschen wrote:
> > - Improved performance in terms of SHA512 checksum computation.
> 
> Thanks for this, but how was it done?

It was embarrassingly simple:

https://sourceware.org/git/gitweb.cgi?p=cygwin-setup.git;a=blobdiff;f=install.cc;h=715d5fe2d12f9e9b7216b7fcbe09f7cd3758123f;hp=aa7c2e91a050ac0e41d59bd2241000da7aaa1456;hb=8648b05caf47865394d76822dea7b37e5cc1282e;hpb=0c7564874d74ecbf410edb7165a26595f53a03f5


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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Re: [ANNOUNCEMENT] Updated: setup.exe (Release 2.871)

[Warren Young]

On May 31, 2015, at 4:24 AM, Corinna Vinschen <corinna-cygwin@cygwin.com> wrote:
> 
> On May 29 17:49, Steven Penny wrote:
>> On Fri, May 29, 2015 at 8:51 AM, Corinna Vinschen wrote:
>>> - Improved performance in terms of SHA512 checksum computation.
>> 
>> Thanks for this, but how was it done?
> 
> It was embarrassingly simple:

That reminds me of a case I ran into a few months ago.

I have some UDP stream reception code that works perfectly on Linux.  Someone wanted it on Windows, too, so I ported it in an afternoon, a relatively easy task since Winsock is mostly a superset of BSD sockets, and there wasn’t much to the app besides Standard C++ and sockets code.

It worked fine on my machine, so I shipped it off, confident that it would work just as well as the Linux version.

Then I start getting field reports about dropped packets whenever the machine wasn’t perfectly idle while running the app.

This is not a high data rate application.  With the 8 kiB buffers I was using — a perfectly sensible size for UDP — it would take about 3 ms to overflow a buffer.  That’s approximately forever in CPU time, so I felt it was more than adequate, even considering multitasking overheads.

In the end, I had to increase the UDP stack buffers for the Windows port to 64 kiB to get it to work reliably on Windows, which effectively increased the buffer time to ~23 ms.

That means the time-slice delay was somewhere between 3 and 22 ms!  That’s on the scale of HDD head seek times, one of the slowest things a computer does!
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