KNL specific fix: disable generating INC and DEC instructions on Xeon Phi and Silvermont CPUs

[Kandu, Rahul]

Hi Vladimir,

Thanks. Fixed the indents- no tabs in the code change. Please find the updated webrev below.
Openjdk bug location: https://bugs.openjdk.java.net/browse/JDK-8182138
Webrev for the code change: http://cr.openjdk.java.net/~vdeshpande/8182138/webrev.01/

regards,
Rahul

From: Vladimir Kozlov [mailto:vladimir.kozlov at oracle.com]
Sent: Thursday, June 15, 2017 2:10 PM
To: Kandu, Rahul <rahul.kandu at intel.com>; hotspot-compiler-dev at openjdk.java.net
Subject: Re: KNL specific fix: disable generating INC and DEC instructions on Xeon Phi and Silvermont CPUs


Hi Rahul

Please fix indents - don't use tabs.

Vladimir
On 6/15/17 1:14 PM, Kandu, Rahul wrote:
Hi all,

The following patch disables generating INC, DEC instructions on Xeon Phi and Silvermont ATOM based CPUs. We have currently identified that using INC and DEC can suffer from unexpected performance drops on certain processors which don't optimize for partial write flags. This patch disables generation of these two instructions as they are more commonly used at loop increment/decrement.
Patch provides 3.65% better performance on Knights Landing CPU on SPECjvm2008 composite score as per runs below on the latest openjdk source.

Openjdk bug location: https://bugs.openjdk.java.net/browse/JDK-8182138
Webrev for the code change: http://cr.openjdk.java.net/~vdeshpande/8182138/webrev.00/<http://cr.openjdk.java.net/%7Evdeshpande/8182138/webrev.00/>

Scores:


6/10 jdk10 code (no change)

6/10 jdk10code with this patch


run1

run2

run3

geomean

run1

run2

run3

geomean

lu.small

1503.79

1500.62

1494.98

1499.792

lu.small

1478.48

1493.78

1509.2

1493.767

sor.small

2417.24

2372.1

2356.47

2381.798

sor.small

2436.89

2434.46

2446.88

2439.404

sparse.small

606.35

635.19

595.44

612.099

sparse.small

681.96

728.02

671.41

693.3673

fft.small

1463.55

1406.43

1173.63

1341.793

fft.small

1220.14

1425.19

1190.06

1274.335

monte_carlo

823.66

825.96

761.26

803.0575

monte_carlo

939.53

923

934.76

932.4041

sparse.large

159.45

139.83

155.76

151.4352

sparse.large

100.66

150.22

179.79

139.5672

fft.large

419.19

425.81

432.6

425.8315

fft.large

433.11

424.72

429.07

428.953

sor.large

416.31

262.98

271.31

309.6957

sor.large

366.6

397.67

352.75

371.8725

lu.large

116.46

127.51

129.33

124.3007

lu.large

124.2

122.69

124.1

123.6614

transform

1056.64

1066.6

1021.08

1047.923

transform

1015.85

1056.42

1049.42

1040.412

validation

1371.86

1898.49

1971.28

1725.131

validation

2088.81

2178.14

2112.95

2126.301

aes

276.67

255.84

299.78

276.8499

aes

261.5

258.95

290.17

269.8444

rsa

1041.29

1069.51

1069.26

1059.937

rsa

1091.45

1089.15

1095.52

1092.037

signverify

2583.7

2592.98

2586.34

2587.67

signverify

2660.73

2664.17

2634.47

2653.09

compress

817.65

817.44

816.55

817.2132

compress

852.55

847.61

894.59

864.6626

serial

608.48

586.62

615.37

603.3646

serial

627.19

605.21

619.31

617.1695

sunflow

371.28

373.03

373.04

372.4491

sunflow

368.59

381.78

369.64

373.289

mpegaudio

743.85

734.46

752.62

743.6064

mpegaudio

775.45

773.35

776.98

775.2586

derby

1929.9

1901.28

1922.56

1917.875

derby

1927.97

1865.47

1919.17

1904.002

Total

780.54

779.91

786.98

782.4702

Total

801

812.98

819

810.9587

3.65% improvement


regards,
Rahul


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