Re: Linking with gcc 4.1.1 is very slow

[Paul Pluzhnikov]

Sven Krueger <sk1@delair.de> writes:

> For example linking one
> of the bigger libraries takes about 30 seconds on gcc 4.0 but 5 minutes on
> gcc 4.1.
>
> I'm quite sure that it's neither a problem of the system nor of the linker
> itself. Compling the c++-Files with gcc 4.0 and linking them with 4.1 is as
> fast as before. But compling with 4.1 and linking with 4.0 is very slow,
> too.

Are you performing 'compile and link with 4.1' vs. 
'compile with 4.1 link with 4.0' on the same machine?

I suspect not. Note that NFS has huge performance implications:
linking on a local file system is often 50 times faster than
over NFS.

> There seems to be a problem with the compiler ...? I'm using -O0 while
> developping, so there should be no optimization. Perhaps there is a new
> magic switch in 4.1 to switch off some of the new optimizations (like ipa),
> which I have not found yet ???

I doubt very much that any such optimization is happening.

You can run "size" and "nm" over gcc-4.0 and 4.1 compiled objects;
the differences should be minimal. If they are minimal, compiler has
nothing to do with the problem, and you should look at the rest of
the "system environment".

While link is happening, see what is happening in "top".
If "ld" is not consuming much of the CPU, see what it's waiting
for with "strace".

Cheers,
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