Il 5/20/2013 3:28 AM, Alan W. Irwin ha scritto:
On 2013-05-19 21:06-0000 David Cole wrote:
With regard to your frustration with Cygwin speed, I must say I have similar frustrations with how fast commands execute under bash.exe. That issue appears to be entirely due to startup latency. For example, here is a comparison of "cmake --version" results on Linux versus running that same command under bash.exe on Wine. software@raven> time cmake --version cmake version 2.8.10.2 real 0m0.008s user 0m0.000s sys 0m0.004s bash.exe-3.1$ time cmake --version cmake version 2.8.10.2 real 0m0.197s user 0m0.000s sys 0m0.040s These results were determined with a CMake version I built myself on Linux and a downloaded Windows binary (built by Kitware with Microsoft proprietary compilers) on MinGW/MSYS/Wine, but in the past I have also gotten similar bad results for a CMake version that I built myself on MinGW/MSYS/Wine, and there are similar bad startup latency results (0.2 seconds just to execute the --version option for the command which is a factor of ~25 slower than the corresponding Linux result) for all other heavily used build commands such as gcc and make. So this is a general bash.exe issue and not a cmake issue, and it a real killer of build speeds since cmake and gcc are often invoked during the build process (e.g., to provide progress reports, to make a quick build test, or to actually make a build containing many separate small source files ) in a way that is completely dominated by the bad startup latency numbers above. At this point I don't know whether this startup latency issue is due to an issue with bash.exe on Wine or a more general bash.exe issue on Windows, and if anybody hear could do such a simple "time cmake --version" test for a MSYS/bash.exe environment on Microsoft Windows to see whether the result is nearer 0.200 seconds or 25 times faster that might confirm or eliminate Wine as the culprit.
the slowness at startup on cywin is mainly due the fork implementation http://cygwin.com/faq/faq-nochunks.html#faq.api.fork unfortunately windows makes a real fork implementation very inefficient.
Alan __________________________ Alan W. Irwin
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