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| Subject: | Re: [ANNOUNCEMENT] Updated: setup.exe (Release 2.871) |
| From: | Warren Young <wyml AT etr-usa DOT com> |
| In-Reply-To: | <20150531102453.GA4323@calimero.vinschen.de> |
| Date: | Mon, 1 Jun 2015 14:05:08 -0600 |
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On May 31, 2015, at 4:24 AM, Corinna Vinschen <corinna-cygwin AT cygwin DOT 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! -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
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