Re: Really slow direct unformatted output under MS Windows:(

[Tobias Burnus <burnus at net-b dot de>]

Dear Delbert,

Delbert Franz wrote:
> I did find some recent activity on the mailing list about release
> 4.7.0 and slow I/O.  Perhaps the issue is under active review.

For the GCC 4.6.0, a fix for another problem causes a massive slow down 
of I/O performance under certain circumstances; the slow down was due to 
_commit(), which not only flushes the buffers but also asks the 
operating system to write the data to the hard disc. This issue has been 
fixed just before the GCC 4.6.2 release (2011-10-26).

A similar patch which even reduces the number of _commit() calls further 
has been committed very recently for GCC 4.7 - I think either today or 
yesterday. (The GCC 4.7.0 will be released around March/April 2012; 
since Tuesday, GCC has entered the stabilization phase for the 4.7 
release ["stage 3"].)

Thus, it is probably worthwhile to try your program with GCC 4.6.2 or a 
very recent GCC 4.7 snapshot.

Depending on your program, the cause could be also a different one such 
that the update might not help for this specific problem. If the problem 
still occurs with 4.6.2 or 4.7, we are very interested in details and/or 
a sample program.

Tobias