Messages in this thread | | | Date | Mon, 03 Feb 2003 15:05:06 -0800 | From | "Martin J. Bligh" <> | Subject | gcc 2.95 vs 3.21 performance |
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People keep extolling the virtues of gcc 3.2 to me, which I'm reluctant to switch to, since it compiles so much slower. But it supposedly generates better code, so I thought I'd compile the kernel with both and compare the results. This is gcc 2.95 and 3.2.1 from debian unstable on a 16-way NUMA-Q. The kernbench tests still use 2.95 for the compile-time stuff.
The results below leaves me distinctly unconvinced by the supposed merits of modern gcc's. Not really better or worse, within experimental error. But much slower to compile things with.
Kernbench-2: (make -j N vmlinux, where N = 2 x num_cpus) Elapsed User System CPU 2.5.59 46.08 563.88 118.38 1480.00 2.5.59-gcc3.2 45.86 563.63 119.58 1489.33
Kernbench-16: (make -j N vmlinux, where N = 16 x num_cpus) Elapsed User System CPU 2.5.59 47.45 568.02 143.17 1498.17 2.5.59-gcc3.2 47.15 567.41 143.72 1507.50
DISCLAIMER: SPEC(tm) and the benchmark name SDET(tm) are registered trademarks of the Standard Performance Evaluation Corporation. This benchmarking was performed for research purposes only, and the run results are non-compliant and not-comparable with any published results.
Results are shown as percentages of the first set displayed
SDET 1 (see disclaimer) Throughput Std. Dev 2.5.59 100.0% 0.8% 2.5.59-gcc3.2 95.3% 5.2%
SDET 2 (see disclaimer) Throughput Std. Dev 2.5.59 100.0% 0.6% 2.5.59-gcc3.2 91.9% 7.1%
SDET 4 (see disclaimer) Throughput Std. Dev 2.5.59 100.0% 5.7% 2.5.59-gcc3.2 98.8% 5.3%
SDET 8 (see disclaimer) Throughput Std. Dev 2.5.59 100.0% 1.4% 2.5.59-gcc3.2 105.3% 4.7%
SDET 16 (see disclaimer) Throughput Std. Dev 2.5.59 100.0% 1.7% 2.5.59-gcc3.2 103.1% 1.8%
SDET 32 (see disclaimer) Throughput Std. Dev 2.5.59 100.0% 1.5% 2.5.59-gcc3.2 101.0% 1.6%
SDET 64 (see disclaimer) Throughput Std. Dev 2.5.59 100.0% 0.7% 2.5.59-gcc3.2 103.1% 1.1%
SDET 128 (see disclaimer) Throughput Std. Dev
NUMA schedbench 4: AvgUser Elapsed TotalUser TotalSys 2.5.59 0.00 38.88 82.78 0.65 2.5.59-gcc3.2 0.00 41.80 107.76 0.73
NUMA schedbench 8: AvgUser Elapsed TotalUser TotalSys 2.5.59 0.00 49.30 247.80 1.93 2.5.59-gcc3.2 0.00 38.00 229.83 2.11
NUMA schedbench 16: AvgUser Elapsed TotalUser TotalSys 2.5.59 0.00 57.37 843.12 3.77 2.5.59-gcc3.2 0.00 57.28 839.21 2.85
NUMA schedbench 32: AvgUser Elapsed TotalUser TotalSys 2.5.59 0.00 116.99 1805.79 6.05 2.5.59-gcc3.2 0.00 118.44 1788.09 6.25
NUMA schedbench 64: AvgUser Elapsed TotalUser TotalSys 2.5.59 0.00 235.18 3632.73 15.45 2.5.59-gcc3.2 0.00 234.55 3633.76 15.02
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And with the same kernel, comparing the compile times for gcc 2.95 to 3.2
Kernbench-2: (make -j N vmlinux, where N = 2 x num_cpus) Elapsed User System CPU gcc2.95 46.08 563.88 118.38 1480.00 gcc3.21 69.93 923.17 114.36 1483.17
Kernbench-16: (make -j N vmlinux, where N = 16 x num_cpus) Elapsed User System CPU gcc2.95 47.45 568.02 143.17 1498.17 gcc3.21 71.44 926.45 134.89 1485.33
pft.
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