Tomas Hajny пишет:
On Thu, July 15, 2010 14:06, Graeme Geldenhuys wrote:
Op 2010-07-15 06:26, Sergei Gorelkin het geskryf:
Message processing indeed includes some overhead, but this is not #1
bottleneck to worry about.
Maybe #10 or so.
Well, any optimization is better than none. Irrespective of where you rank
it, one has to start somewhere.
Have I misunderstood something, or is this optimization really just about
the fact that message loading is not necessary if the compiler is
requested to output no messages at all? Even if this (probably extremely
rare!) case happens, the difference must be completely negligible unless
you perform very many compilations of simple and short source files
without further dependencies (which doesn't sound like a typical use case
to me ;-) ), right?
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).
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.
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.
Regards,
Sergei
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