Re: which pages of the file are in the cache
Re: which pages of the file are in the cache
- Subject: Re: which pages of the file are in the cache
- From: Terry Lambert <email@hidden>
- Date: Tue, 18 Aug 2009 12:25:41 -0700
On Aug 18, 2009, at 10:53 AM, Joel Reymont wrote:
Terry,
It's actually my understanding that the issue is one of having lots
of static constructors which are not precomputed,
What is a non-precomputed static constructor and what is a
precomputed one?
Some compilers also support precomputing the post-constructed value of
static class instances, such that the class starts out initialized,
rather than having to call the constructor at runtime, which costs
compile time but saves start time. If you have a lot of static or
global constructors, this can cause considerable overhead constructing
things before your program actually starts running. You can find most
cases where this might be an issue with -Wglobal-constructors.
Based on your optimization level, you will have two options that might
be on or off with regard to constructors; one is -fno-elide-
constructors, which is my understanding is the case witho no specific
optimization enabled. If this setting is in play, then g++ will
always create a temporary and use a copy constructor to initialize
objects of the same type. The other is the inlining options, which
can greatly impact recursive templates.
PS: Hopefully, you don't use exceptions or rtti, and can turn them
off; otherwise they also cause a lot of overhead. The dwarf stuff
that is used for exception unwinding is pretty heavy weight.
-- Terry
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