[Python-Dev] Profile Guided Optimization active by-default

Patrascu, Alecsandru alecsandru.patrascu at intel.com
Sun Aug 23 08:59:25 CEST 2015

I removed the zip file and uploaded the patches individually. 


From: Brett Cannon [mailto:brett at python.org] 
Sent: Sunday, August 23, 2015 4:47 AM
To: Patrascu, Alecsandru; python-dev at python.org
Subject: Re: [Python-Dev] Profile Guided Optimization active by-default

On Sat, 22 Aug 2015 at 11:10 Patrascu, Alecsandru <alecsandru.patrascu at intel.com> wrote:
I'm sorry, I forgot to mention this, I already opened an issue and the patches are uploaded [1].

[1] http://bugs.python.org/issue24915

Great, thanks Alecandru. Do please follow Stefan's comment, though, and upload the patch files directly and not as a zip file. That way we can use our code review tool to do a proper review of the patches.


From: Brett Cannon [mailto:brett at python.org]
Sent: Saturday, August 22, 2015 9:00 PM
To: Patrascu, Alecsandru; python-dev at python.org
Subject: Re: [Python-Dev] Profile Guided Optimization active by-default

I just realized I didn't see anyone say it, but please upload the patches to bugs.Python.org for easier tracking and reviewing.

On Sat, Aug 22, 2015, 08:01 Patrascu, Alecsandru <alecsandru.patrascu at intel.com> wrote:
Hi All,

This is Alecsandru from Server Scripting Languages Optimization team at Intel Corporation.

I would like to submit a request to turn-on Profile Guided Optimization or PGO as the default build option for Python (both 2.7 and 3.6), given its performance benefits on a wide variety of workloads and hardware.  For instance, as shown from attached sample performance results from the Grand Unified Python Benchmark, >20% speed up was observed.  In addition, we are seeing 2-9% performance boost from OpenStack/Swift where more than 60% of the codes are in Python 2.7. Our analysis indicates the performance gain was mainly due to reduction of icache misses and CPU front-end stalls.

Attached is the Makefile patches that modify the all build target and adds a new one called "disable-profile-opt". We built and tested this patch for Python 2.7 and 3.6 on our Linux machines (CentOS 7/Ubuntu Server 14.04, Intel Xeon Haswell/Broadwell with 18/8 cores).  We use "regrtest" suite for training as it provides the best performance improvement.  Some of the test programs in the suite may fail which leads to build fail.  One solution is to disable the specific failed test using the "-x " flag (as shown in the patch)

Steps to apply the patch:
1.  hg clone https://hg.python.org/cpython cpython
2.  cd cpython
3.  hg update 2.7 (needed for 2.7 only)
4.  Copy *.patch to the current directory
5.  patch < python2.7-pgo.patch (or patch < python3.6-pgo.patch)
6.  ./configure
7.  make

To disable PGO
7b. make disable-profile-opt

In the following, please find our sample performance results from latest XEON machine, XEON Broadwell EP.
Hardware (HW):      Intel XEON (Broadwell) 8 Cores

BIOS settings:      Intel Turbo Boost Technology: false
                    Hyper-Threading: false

Operating System:   Ubuntu 14.04.3 LTS trusty

OS configuration:   CPU freq set at fixed: 2.6GHz by
                        echo 2600000 > /sys/devices/system/cpu/cpu*/cpufreq/scaling_min_freq
                        echo 2600000 > /sys/devices/system/cpu/cpu*/cpufreq/scaling_max_freq
                    Address Space Layout Randomization (ASLR) disabled (to reduce run to run variation) by
                        echo 0 > /proc/sys/kernel/randomize_va_space

GCC version:        gcc version 4.8.4 (Ubuntu 4.8.4-2ubuntu1~14.04)

Benchmark:          Grand Unified Python Benchmark (GUPB)
                    GUPB Source: https://hg.python.org/benchmarks/

Python2.7 results:
    Python source: hg clone https://hg.python.org/cpython cpython
    Python Source: hg update 2.7
    hg id: 0511b1165bb6 (2.7)
    hg id -r 'ancestors(.) and tag()': 15c95b7d81dc (2.7) v2.7.10
    hg --debug id -i: 0511b1165bb6cf40ada0768a7efc7ba89316f6a5

        Benchmarks          Speedup(%)
        simple_logging      20
        raytrace            20
        silent_logging      19
        richards            19
        chaos               16
        formatted_logging   16
        json_dump           15
        hexiom2             13
        pidigits            12
        slowunpickle        12
        django_v2           12
        unpack_sequence     11
        float               11
        mako                11
        slowpickle          11
        fastpickle          11
        django              11
        go                  10
        json_dump_v2        10
        pathlib             10
        regex_compile       10
        pybench             9.9
        etree_process       9
        regex_v8            8
        bzr_startup         8
        2to3                8
        slowspitfire        8
        telco               8
        pickle_list         8
        fannkuch            8
        etree_iterparse     8
        nqueens             8
        mako_v2             8
        etree_generate      8
        call_method_slots   7
        html5lib_warmup     7
        html5lib            7
        nbody               7
        spectral_norm       7
        spambayes           7
        fastunpickle        6
        meteor_contest      6
        chameleon           6
        rietveld            6
        tornado_http        5
        unpickle_list       5
        pickle_dict         4
        regex_effbot        3
        normal_startup      3
        startup_nosite      3
        etree_parse         2
        call_method_unknown 2
        call_simple         1
        json_load           1
        call_method         1

Python3.6 results
    Python source: hg clone https://hg.python.org/cpython cpython
    hg id: 96d016f78726 tip
    hg id -r 'ancestors(.) and tag()': 1a58b1227501 (3.5) v3.5.0rc1
    hg --debug id -i: 96d016f78726afbf66d396f084b291ea43792af1

        Benchmark           Speedup(%)
        fastunpickle        22.94
        fastpickle          21.67
        json_load           17.64
        simple_logging      17.49
        meteor_contest      16.67
        formatted_logging   15.33
        etree_process       14.61
        raytrace            13.57
        etree_generate      13.56
        chaos               12.09
        hexiom2             12
        nbody               11.88
        json_dump_v2        11.24
        richards            11.02
        nqueens             10.96
        fannkuch            10.79
        go                  10.77
        float               10.26
        regex_compile       9.8
        silent_logging      9.63
        pidigits            9.58
        etree_iterparse     9.48
        2to3                8.44
        regex_v8            8.09
        regex_effbot        7.88
        call_simple         7.63
        tornado_http        7.38
        etree_parse         4.92
        spectral_norm       4.72
        normal_startup      4.39
        telco               3.88
        startup_nosite      3.7
        call_method         3.63
        unpack_sequence     3.6
        call_method_slots   2.91
        call_method_unknown 2.59
        iterative_count     0.45
        threaded_count      -2.79

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