[Bug target/32086] New: 10% to 20% Performance Regression Between 4.1.3 and 4.3

[Bug target/32086] New: 10% to 20% Performance Regression Between 4.1.3 and 4.3

[burnus at gcc dot gnu dot org]

The program induct.f90 of the Polyhedron testsuite,
http://www.polyhedron.co.uk/pb05/polyhedron_benchmark_suite.html, runs about
10% slower under 4.3 than under 4.1.3 (20070430 prerelease SUSE Linux).

A cut-down testcase "test2.f90 (attachment 13611 of PR 32084) shows the same
result. At least for the testcase, the original tree is almost identical for
4.3 and 4.1.3 which means that the difference must be the middle or backend.

Timings (w/o "volatile"):

a) gfortran -march=opteron -ffast-math -funroll-loops -ftree-vectorize
-ftree-loop-linear -msse3 -O3

induct.f90: 51.65 [100%] vs 46.94 [ 90%] for gfortran 4.3 vs. 4.1.3
test2.f90:   4.60 [100%] vs  4.18 [ 91%]

b) gfortran -m32 -march=opteron -ffast-math -funroll-loops -ftree-vectorize
-ftree-loop-linear -O3

induct.f90: 61.41 [100%] vs 46.94 [ 76%]
test2.f90:   5.45 [100%] vs  4.54 [ 83%]

c) gfortran -m32 -march=opteron -ffast-math -funroll-loops -ftree-vectorize
-ftree-loop-linear -msse3 -mfpmath=sse -O3

induct.f90: 46.12 [100%] vs 46.94 [102%]  (4.3 is better :-)
test2.f90:   4.14 [100%] vs  3.96 [ 96%]

(For the other polyhedron test cases, the performance loss is less: tfft 4%
slower, protein 3%, doduc 3%, channel 2%; in total 4.3 is faster, for fatigue
4.1.3 takes twice as long as 4.3. See:
http://physik.fu-berlin.de/~tburnus/gcc-trunk/benchmark/#rt)


-- 
           Summary: 10% to 20% Performance Regression Between 4.1.3 and 4.3
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: burnus at gcc dot gnu dot org
GCC target triplet: x86_64-unknown-linux-gnu
OtherBugsDependingO 32084
             nThis:


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32086

[Bug target/32086] [4.3 Regression] 10% to 20% Performance Regression Between 4.1.3 and 4.3

[jsm28 at gcc dot gnu dot org]

-- 

jsm28 at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|10% to 20% Performance      |[4.3 Regression] 10% to 20%
                   |Regression Between 4.1.3 and|Performance Regression
                   |4.3                         |Between 4.1.3 and 4.3
   Target Milestone|---                         |4.3.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32086

[Bug target/32086] [4.3 Regression] 10% to 20% Performance Regression Between 4.1.3 and 4.3

[mmitchel at gcc dot gnu dot org]

-- 

mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32086

[Bug target/32086] [4.3 Regression] 10% to 20% Performance Regression Between 4.1.3 and 4.3

[ubizjak at gmail dot com]

------- Comment #1 from ubizjak at gmail dot com  2007-11-29 08:09 -------
(In reply to comment #0)

> b) gfortran -m32 -march=opteron -ffast-math -funroll-loops -ftree-vectorize
> -ftree-loop-linear -O3
> 
> induct.f90: 61.41 [100%] vs 46.94 [ 76%]
> test2.f90:   5.45 [100%] vs  4.54 [ 83%]

I have run the test compiled with above options, with and without
-fvect-cost-model, but on Xeon 3.2G in 32bit mode:

w/o -fvect-cost-model:

user    1m40.906s

w/ -fvect-cost-model:

user    0m46.439s


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32086

[Bug target/32086] [4.3 Regression] 10% to 20% Performance Regression Between 4.1.3 and 4.3

[bonzini at gnu dot org]

------- Comment #2 from bonzini at gnu dot org  2007-11-30 05:41 -------
What were the benchmarks where the cost model was slower?


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bonzini at gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bonzini at gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32086

[Bug target/32086] [4.3 Regression] 10% to 20% Performance Regression Between 4.1.3 and 4.3

[ubizjak at gmail dot com]

------- Comment #3 from ubizjak at gmail dot com  2007-11-30 06:42 -------
(In reply to comment #1)

> w/ -fvect-cost-model:
> user    0m46.439s

Looking a bit into generated code, it looks that -fect-cost-model effectively
disables all interesting vectorizations, effectively -fno-tree-vectorize.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32086

[Bug target/32086] [4.3 Regression] 10% to 20% Performance Regression Between 4.1.3 and 4.3

[bonzini at gnu dot org]

------- Comment #4 from bonzini at gnu dot org  2007-11-30 07:17 -------
So -fvect-cost-model is doing its job.  The vectorizations must not be
profitable, or are they?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32086

[Bug target/32086] [4.3 Regression] 10% to 20% Performance Regression Between 4.1.3 and 4.3

[ubizjak at gmail dot com]

------- Comment #5 from ubizjak at gmail dot com  2007-11-30 10:27 -------
gfortran -march=opteron -ffast-math -funroll-loops -ftree-loop-linear -msse3
-O3 -mfpmath=sse induct.f90:
user    1m32.226s
gfortran -march=opteron -ffast-math -funroll-loops -ftree-loop-linear -msse3
-O3 -mfpmath=sse -fno-tree-vectorize induct.f90
user    0m58.492s
fortran -march=opteron -ffast-math -funroll-loops -ftree-loop-linear -msse3 -O3
-mfpmath=387 induct.f90
user    1m40.906s
gfortran -march=opteron -ffast-math -funroll-loops -ftree-loop-linear -msse3
-O3 -mfpmath=387 -fno-tree-vectorize induct.f90
user    0m46.439s
gfortran -march=opteron -ffast-math -funroll-loops -ftree-loop-linear -msse3
-O3 -mfpmath=sse -fvect-cost-model induct.f90
user    0m58.168s
gfortran -march=opteron -ffast-math -funroll-loops -ftree-loop-linear -msse3
-O3 -mfpmath=387 -fvect-cost-model induct.f90
user    0m46.415s

All on:

Family: 15 Model: 4 Stepping: 10 Type: 0 Brand: 0
CPU Model: Pentium 4 D (Foster) Original OEM
Processor name string: Intel(R) Xeon(TM) CPU 3.60GHz

(so -march=opteron is a bit misleading)

I'd say that vectorizer cost model is doing its job pretty well.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32086

[Bug target/32086] [4.3 Regression] 10% to 20% Performance Regression Between 4.1.3 and 4.3

[bonzini at gnu dot org]

------- Comment #6 from bonzini at gnu dot org  2007-11-30 10:59 -------
Looking at
http://physik.fu-berlin.de/~tburnus/gcc-trunk/benchmark/gfortran-run.dat and
http://physik.fu-berlin.de/~tburnus/gcc-trunk/benchmark/gfortranVecCost-run.dat
I think we should turn on cost model by default, at least for i386.

Uros?


-- 

bonzini at gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2007-11-30 10:59:33
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32086

[Bug target/32086] [4.3 Regression] 10% to 20% Performance Regression Between 4.1.3 and 4.3

[ubizjak at gmail dot com]

------- Comment #7 from ubizjak at gmail dot com  2007-11-30 13:20 -------
This is with latest SVN:

   Benchmark
        Name     387       387c      sse       ssec
   ---------   -------   -------   -------   -------
          ac     16.57     16.57     22.66     22.65
      aermod     55.85     54.72     50.23     51.08
         air     14.95     15.02     15.92     15.94
    capacita     78.60     78.55     81.89     81.95
     channel      9.90      9.78      9.90      9.65
       doduc     59.82     59.65     67.81     68.97
     fatigue     20.06     18.27     21.65     21.27
     gas_dyn     11.47     11.35     10.62     10.68
      induct     60.60     50.92     73.82     58.74
       linpk     27.26     27.20     28.24     28.17
        mdbx     30.41     30.36     33.33     33.23
          nf     33.63     33.69     31.97     32.03
     protein     73.16     72.87     72.67     72.76
      rnflow     57.18     57.18     42.19     42.46
    test_fpu     20.71     20.86     21.61     21.54
        tfft      4.86      5.10      4.92      5.11

                 27.48     27.03     28.26     27.93

gcc version 4.3.0 20071130 (experimental) [trunk revision 130533] (GCC)

Family: 15 Model: 4 Stepping: 10 Type: 0 Brand: 0
CPU Model: Pentium 4 D (Foster) Original OEM
Processor name string: Intel(R) Xeon(TM) CPU 3.60GHz

Compile Command :
-march=opteron -ffast-math -funroll-loops -ftree-loop-linear -msse3 -O3

387 : -mfpmath=387
387c: -mfpmath=387 -fvec-cost-model
sse : -mfpmath=sse
ssec: -mfpmath=sse -fvec-cost-model


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32086

[Bug target/32086] [4.3 Regression] 10% to 20% Performance Regression Between 4.1.3 and 4.3

[bonzini at gnu dot org]

------- Comment #8 from bonzini at gnu dot org  2007-11-30 13:30 -------
Testing a one-liner.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32086

[Bug target/32086] [4.3 Regression] 10% to 20% Performance Regression Between 4.1.3 and 4.3

[dominiq at lps dot ens dot fr]

------- Comment #9 from dominiq at lps dot ens dot fr  2007-11-30 15:23 -------
> I think we should turn on cost model by default, at least for i386.

Although the information on cost model are very scarce in the gcc manual, if
its goal is to avoid too costly vectorization, it should certainly turned on by
default.  And probably if this increases the execution time, the cost model
would need some tuning.  Concerning the induct code it is not a good test case
on PPC since it uses double FP.  On a 2.16Ghz Core2Duo I get for induct:

-O3 -ffast-math -funroll-loops induct.f90
        93.192u 0.066s 1:33.28 99.9%    0+0k 0+1io 0pf+0w
-O3 -ffast-math -funroll-loops -fvect-cost-model induct.f90
        73.453u 0.107s 1:13.57 99.9%    0+0k 0+1io 0pf+0w
-O3 -ffast-math -funroll-loops -mfpmath=387 induct.f90
        105.564u 0.128s 1:45.69 99.9%   0+0k 0+1io 0pf+0w
-O3 -ffast-math -funroll-loops -mfpmath=387 -fvect-cost-model induct.f90
        79.162u 0.088s 1:19.25 99.9%    0+0k 0+0io 0pf+0w


With the patch in comment #5 of PR34265, the timings are:
without -mfpmath=387  and with or without -fvect-cost-model
        37.014u 0.065s 0:37.08 99.9%    0+0k 0+0io 0pf+0w
with -mfpmath=387  and with or without -fvect-cost-model
        39.820u 0.071s 0:39.89 100.0%   0+0k 0+0io 0pf+0w


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32086

[Bug target/32086] [4.3 Regression] 10% to 20% Performance Regression Between 4.1.3 and 4.3

[bonzini at gcc dot gnu dot org]

------- Comment #10 from bonzini at gnu dot org  2007-12-10 08:34 -------
Subject: Bug 32086

Author: bonzini
Date: Mon Dec 10 08:34:37 2007
New Revision: 130738

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=130738
Log:
2007-12-10  Paolo Bonzini  <bonzini@gnu.org>

        PR target/32086
        * config/i386/i386.c (override_options): Enable -fvect-cost-model.

2007-12-10  Paolo Bonzini  <bonzini@gnu.org>

        PR target/32086
        * gcc.dg/vect/vect.exp (DEFAULT_VECTCFLAGS): Disable cost model.
        * g++.dg/vect/vect.exp (DEFAULT_VECTCFLAGS): Disable cost model.
        * gfortran.dg/vect/vect.exp (DEFAULT_VECTCFLAGS): Disable cost model.


Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/i386/i386.c
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/g++.dg/vect/vect.exp
    trunk/gcc/testsuite/gcc.dg/vect/vect.exp
    trunk/gcc/testsuite/gfortran.dg/vect/vect.exp


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32086

[Bug target/32086] [4.3 Regression] 10% to 20% Performance Regression Between 4.1.3 and 4.3

[bonzini at gnu dot org]

------- Comment #11 from bonzini at gnu dot org  2007-12-10 08:36 -------
committed, cost model now enabled for i386.


-- 

bonzini at gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32086

[Bug target/32086] [4.3 Regression] 10% to 20% Performance Regression Between 4.1.3 and 4.3

[dominiq at lps dot ens dot fr]

------- Comment #12 from dominiq at lps dot ens dot fr  2007-12-10 16:03 -------
> committed, cost model now enabled for i386.

Is it working for Intel Core2Duo? At revision 130743 and

Using built-in specs.
Target: i686-apple-darwin9
Configured with: ../gcc-4.3-work/configure --prefix=/opt/gcc/gcc4.3w
--mandir=/opt/gcc/gcc4.3w/share/man --infodir=/opt/gcc/gcc4.3w/share/info
--build=i686-apple-darwin9 --enable-languages=c,c++,fortran,objc,obj-c++,java
--with-gmp=/sw --with-libiconv-prefix=/sw --with-system-zlib
--x-includes=/usr/X11R6/include --x-libraries=/usr/X11R6/lib
Thread model: posix
gcc version 4.3.0 20071210 (experimental) (GCC) 

for 'gfc -O3 -ffast-math -funroll-loops induct.f90' (with/without
-fvect-cost-model), the execution time is:

93.986u 0.051s 1:34.04 99.9%    0+0k 0+0io 0pf+0w

while for 'gfc -O3 -ffast-math -funroll-loops --param min-vect-loop-bound=2
induct.f90', it is:

76.345u 0.048s 1:16.39 99.9%    0+0k 0+0io 0pf+0w

If yes, the cost model should be tuned for Core2Duo. If no, did I do something
wrong with the configure?

Should I open a new PR for these questions?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32086

[Bug target/32086] [4.3 Regression] 10% to 20% Performance Regression Between 4.1.3 and 4.3

[bonzini at gnu dot org]

------- Comment #13 from bonzini at gnu dot org  2007-12-10 16:37 -------
I think so.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32086

[Bug target/32086] [4.3 Regression] 10% to 20% Performance Regression Between 4.1.3 and 4.3

[howarth at nitro dot med dot uc dot edu]

------- Comment #14 from howarth at nitro dot med dot uc dot edu  2007-12-10 16:41 -------
Dominique,
    What do you get when you use the proposed early-complete-unrolling patch
from PR34265 and is there any movement towards getting some form of that patch
into gcc trunk?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32086

[Bug target/32086] [4.3 Regression] 10% to 20% Performance Regression Between 4.1.3 and 4.3

[rguenth at gcc dot gnu dot org]

------- Comment #15 from rguenth at gcc dot gnu dot org  2007-12-10 17:07 -------
Early unrolling will be addressed earliest in the next stage1.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32086