High Activity of setprogname

Ryan Johnson ryanjohn@ece.cmu.edu
Thu May 19 17:42:00 GMT 2011

On 2:59 PM, Sravan Bhamidipati wrote:
> Terminals like mintty and rxvt are doing an unusual amount of context
> switching and consuming a lot of CPU cycles even in idle time. Process
> Explorer suggests that this activity is largely attributable to
> "cygwin1.dll!setprogname". Could this be something that should not or
> need not be done? (Running cygwin.bat directly to use Cygwin doesn't
> show such activity.)
> Most recently I've been seeing this behavior with Mintty v0.97, Cygwin
> v1.7.9-1, Windows 7 Ultimate SP1 (x64, Build Version: 6.1.7601 Service
> Pack 1 Build 7601). However I've noticed this in a few older versions
> of Mintty, Cygwin as well, even on Windows XP.
> You can also view the mintty thread where this discussion began:
> http://code.google.com/p/mintty/issues/detail?id=265
The running code is related to select() (try running strace -mselect 
mintty to see for yourself).

A little poking around with windbg and gdb shows that select.cc:650 
(thread_pipe) is the culprit: select itself is called with infinite 
timeout; somebody more knowledgeable than me will have to explain why 
thread_pipe would return data so often for an idle process, however.


P.S. Windows has no clue about gcc's symbols, which is why you got 
setprogname+0x2620 instead of something that made sense.

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