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Re: Gcc 3.1 performance regressions with respect to 2.95.3
- From: Peter Schmid <schmid at snake dot iap dot physik dot tu-darmstadt dot de>
- To: Jan Hubicka <jh at suse dot cz>
- Cc: Jason Merrill <jason at redhat dot com>, <gcc at gcc dot gnu dot org>, <libstdc++ at gcc dot gnu dot org>
- Date: Wed, 20 Mar 2002 05:04:50 +0100 (CET)
- Subject: Re: Gcc 3.1 performance regressions with respect to 2.95.3
I applied your cross jumping patch, did a full bootstrap and ran the
regression test suite. There are no regressions.
Here are the results for the stepanov test. Surprisingly, when the -O
optimization gains the most speed from your patch, resulting in the
fastest executable. Now, gcc 3.1 has about the same performance as
gcc 2.95, but at the -O3 level. Why have the additional optimizations
no net effect in comparison to -O? Do you have an idea what is going wrong?
Thank you for enhancing the performance. I strongly suggest your patch
should go in.
Hope this helps,
Peter Schmid
-O
test absolute additions ratio with
number time per second test0
0 0.45sec 111.11M 1.00
1 0.46sec 108.70M 1.02
2 0.46sec 108.70M 1.02
3 0.45sec 111.11M 1.00
4 0.48sec 104.17M 1.07
5 0.53sec 94.34M 1.18
6 0.50sec 100.00M 1.11
7 0.50sec 100.00M 1.11
8 0.51sec 98.04M 1.13
9 0.46sec 108.70M 1.02
10 0.45sec 111.11M 1.00
11 0.45sec 111.11M 1.00
12 0.48sec 104.17M 1.07
mean: 0.47sec 105.33M 1.05
Total absolute time: 6.18 sec
Abstraction Penalty: 1.05 was 1.12 without your patch applied.
-O2
test absolute additions ratio with
number time per second test0
0 0.44sec 113.64M 1.00
1 0.45sec 111.11M 1.02
2 0.47sec 106.38M 1.07
3 0.62sec 80.65M 1.41
4 0.60sec 83.33M 1.36
5 0.56sec 89.29M 1.27
6 0.57sec 87.72M 1.30
7 0.56sec 89.29M 1.27
8 0.56sec 89.29M 1.27
9 0.62sec 80.65M 1.41
10 0.60sec 83.33M 1.36
11 0.62sec 80.65M 1.41
12 0.60sec 83.33M 1.36
mean: 0.56sec 90.01M 1.26
Total absolute time: 7.27 sec
Abstraction Penalty: 1.26 was 1.30.
-O3
test absolute additions ratio with
number time per second test0
0 0.44sec 113.64M 1.00
1 0.48sec 104.17M 1.09
2 0.48sec 104.17M 1.09
3 0.61sec 81.97M 1.39
4 0.60sec 83.33M 1.36
5 0.56sec 89.29M 1.27
6 0.56sec 89.29M 1.27
7 0.56sec 89.29M 1.27
8 0.56sec 89.29M 1.27
9 0.60sec 83.33M 1.36
10 0.61sec 81.97M 1.39
11 0.60sec 83.33M 1.36
12 0.60sec 83.33M 1.36
mean: 0.56sec 89.99M 1.26
Total absolute time: 7.26 sec
Abstraction Penalty: 1.26 was 1.28.