[fpc-devel] Messages overhead
DrDiettrich1 at aol.com
Thu Jul 15 22:52:37 CEST 2010
Sergei Gorelkin schrieb:
> The issue was that, whenever compiler needs to output a message, it:
> - loads a messagefile (once in a session)
> - looks up the message by number
> - performs the parameter substitution (this involves AnsiStrings, so is
> somewhat heavy)
> - only then checks if it should really print the resulting string.
> The most amount of messages come from unit search; the system units are
> loaded every time, so you always have about several thousands messages
> loaded and discarded. This was taking a noticeable amount of executed
> CPU instructions (profiled with Valgrind).
This is just what I concluded from a quick glance at the implementation.
> With the patch applied in r9297, I was able to cut the total number of
> executed instructions down by 20%, but that gave no increase in
> perceived speed of compilation. So I decided not to put much more effort
> to this issue.
Good to know :-)
I think that it's time to put aside old experience, and replace it by
up-to-date performance considerations. And since FPC seems to be
optimized and tested very well, even if it doesn't look so at the first
glance, I better concentrate on other tasks.
> Although, modifying the messaging system in a way when CheckVerbosity()
> is called as soon as possible (before parameter substitution and other
> processing) could be beneficial.
Then at least one can be sure that the mentioned overhead can not occur
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