Da li neko koristi Link Time Optimizaciju?

[bmaxa]

Evo recimo na primeru scimark2 sa i bez lto.

/.../forth/sci >>> gcc -Ofast -march=native *.c -o scimark2 -lm                                           [130]
~/.../forth/sci >>> gcc -Ofast -march=native *.c -o scimark2lto -lm --lto
~/.../forth/sci >>> ./scimark2
**                                                              **
** SciMark2 Numeric Benchmark, see http://math.nist.gov/scimark **
** for details. (Results can be submitted to pozo@nist.gov)     **
**                                                              **
Using       2.00 seconds min time per kenel.
Composite Score:         2989.70
FFT             Mflops:  2322.85    (N=1024)
SOR             Mflops:  2312.89    (100 x 100)
MonteCarlo:     Mflops:   684.41
Sparse matmult  Mflops:  3508.10    (N=1000, nz=5000)
LU              Mflops:  6120.24    (M=100, N=100)
~/.../forth/sci >>> ./scimark2lto
**                                                              **
** SciMark2 Numeric Benchmark, see http://math.nist.gov/scimark **
** for details. (Results can be submitted to pozo@nist.gov)     **
**                                                              **
Using       2.00 seconds min time per kenel.
Composite Score:         2681.39
FFT             Mflops:  2339.62    (N=1024)
SOR             Mflops:  2329.67    (100 x 100)
MonteCarlo:     Mflops:  1479.45
Sparse matmult  Mflops:  3198.61    (N=1000, nz=5000)
LU              Mflops:  4059.62    (M=100, N=100)
~/.../forth/sci >>> ls -l scimark2
-rwxr-xr-x 1 bmaxa users 29520 May 30 17:31 scimark2
~/.../forth/sci >>> ls -l scimark2lto
-rwxr-xr-x 1 bmaxa users 23280 May 30 17:31 scimark2lto
~/.../forth/sci >>> strip scimark2
~/.../forth/sci >>> strip scimark2lto
~/.../forth/sci >>> ls -l scimark2lto
-rwxr-xr-x 1 bmaxa users 18576 May 30 17:34 scimark2lto
~/.../forth/sci >>> ls -l scimark2
-rwxr-xr-x 1 bmaxa users 22672 May 30 17:33 scimark2

znaci lto pravi sporije executable ali smanjuje velicinu fajlova. Mislim da ova optimizacija i nema neki benefit
danas kada je memorija tako jeftina i ima je dosta....

 

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