RFR(S): 8205194: Improve the Array Comparison when there is a mismatch at first element.
Paul Sandoz
paul.sandoz at oracle.com
Wed Jun 20 21:29:33 UTC 2018
459 public static int mismatch(float[] a, int aFromIndex,
460 float[] b, int bFromIndex,
461 int length) {
462 int i = 0;
463 if (length > 1) {
464 if (a[aFromIndex] != b[bFromIndex]) {
465 i = 0;
466 } else {
You fold the if/else to;
if (a[aFromIndex] == b[bFromIndex]) {
…
}
same applies in other cases in both source files.
> On Jun 20, 2018, at 1:21 PM, Deshpande, Vivek R <vivek.r.deshpande at intel.com> wrote:
>
> Hi All
>
> I have updated the webrev with all the suggestions, which passes ArraysEqCmpTest.java.
> Earlier webrev failed the same test.
Thanks for confirming.
> This webrev also modifies the BufferMismatch.java in similar way.
Great!
Paul.
> Please take a look and let me know what you think.
>
> Updated webrev is here:
> http://cr.openjdk.java.net/~vdeshpande/vectorizedMismatch_jdk/webrev.01/ <http://cr.openjdk.java.net/~vdeshpande/vectorizedMismatch_jdk/webrev.01/>
> I have also modified the bug with updated webrev.
> Regards,
> Vivek
>
> From: Deshpande, Vivek R
> Sent: Tuesday, June 19, 2018 10:57 AM
> To: Paul Sandoz <paul.sandoz at oracle.com <mailto:paul.sandoz at oracle.com>>; Roger.Riggs at oracle.com <mailto:Roger.Riggs at oracle.com>
> Cc: David Holmes <david.holmes at oracle.com <mailto:david.holmes at oracle.com>>; core-libs-dev at openjdk.java.net <mailto:core-libs-dev at openjdk.java.net>; Viswanathan, Sandhya <sandhya.viswanathan at intel.com <mailto:sandhya.viswanathan at intel.com>>
> Subject: RE: RFR(S): 8205194: Improve the Array Comparison when there is a mismatch at first element.
>
> Hi Roger
>
> I will also test with zero length arrays and let you know.
> Thanks for the input.
>
> Regards,
> Vivek
>
> From: Deshpande, Vivek R
> Sent: Tuesday, June 19, 2018 10:17 AM
> To: 'Paul Sandoz' <paul.sandoz at oracle.com <mailto:paul.sandoz at oracle.com>>
> Cc: David Holmes <david.holmes at oracle.com <mailto:david.holmes at oracle.com>>; core-libs-dev at openjdk.java.net <mailto:core-libs-dev at openjdk.java.net>; Viswanathan, Sandhya <sandhya.viswanathan at intel.com <mailto:sandhya.viswanathan at intel.com>>
> Subject: RE: RFR(S): 8205194: Improve the Array Comparison when there is a mismatch at first element.
>
> Thanks Paul for quick review. I will work on the things you have mentioned and get back soon.
> I will also test this with test/jdk/java/util/Arrays/ArraysEqCmpTest.java.
>
> Regards,
> Vivek
>
> From: Paul Sandoz [mailto:paul.sandoz at oracle.com <mailto:paul.sandoz at oracle.com>]
> Sent: Tuesday, June 19, 2018 9:55 AM
> To: Deshpande, Vivek R <vivek.r.deshpande at intel.com <mailto:vivek.r.deshpande at intel.com>>
> Cc: David Holmes <david.holmes at oracle.com <mailto:david.holmes at oracle.com>>; core-libs-dev at openjdk.java.net <mailto:core-libs-dev at openjdk.java.net>; Viswanathan, Sandhya <sandhya.viswanathan at intel.com <mailto:sandhya.viswanathan at intel.com>>
> Subject: Re: RFR(S): 8205194: Improve the Array Comparison when there is a mismatch at first element.
>
> Hi Vivek,
>
> Thanks for investigating this.
>
> 164 public static int mismatch(boolean[] a,
> 165 boolean[] b,
> 166 int length) {
> 167 int i = 0;
> 168 if (a[i] != b[i])
> 169 return i;
> You might as well replace the use if i with 0 and i think you can move this to be performed when the length is greater than the threshold, that way you don’t impact small arrays below the threshold.
>
> 186 public static int mismatch(boolean[] a, int aFromIndex,
> 187 boolean[] b, int bFromIndex,
> 188 int length) {
> 189 int i = 0;
> 190 if (a[i] != b[i])
> 191 return i;
> This is incorrect. You need to use aFromIndex and bFromIndex.
>
> Do you run the test test/jdk/java/util/Arrays/ArraysEqCmpTest.java? If that passed then we need to strengthen for the case of a mismatch on the first relative element in each array.
>
> Paul.
>
>
> On Jun 19, 2018, at 9:36 AM, Deshpande, Vivek R <vivek.r.deshpande at intel.com <mailto:vivek.r.deshpande at intel.com>> wrote:
>
> Thanks David.
> Sending it to core-libs-dev.
>
> I would like to contribute a patch which improves the array comparison when there is a mismatch for the first element.
> This avoids call to vectorizedMismatch method and gives ~80x speed up.
> Could you please review and sponsor the patch.
> Link to bug:
> https://bugs.openjdk.java.net/browse/JDK-8205194 <https://bugs.openjdk.java.net/browse/JDK-8205194>
> webrev:
> http://cr.openjdk.java.net/~vdeshpande/vectorizedMismatch_jdk/webrev.00/ <http://cr.openjdk.java.net/~vdeshpande/vectorizedMismatch_jdk/webrev.00/>
>
> Regards,
> Vivek
>
> -----Original Message-----
> From: David Holmes [mailto:david.holmes at oracle.com <mailto:david.holmes at oracle.com>]
> Sent: Monday, June 18, 2018 10:32 PM
> To: Deshpande, Vivek R <vivek.r.deshpande at intel.com <mailto:vivek.r.deshpande at intel.com>>; jdk-dev at openjdk.java.net <mailto:jdk-dev at openjdk.java.net>
> Subject: Re: RFR(S): 8205194: Improve the Array Comparison when there is a mismatch at first element.
>
> Hi Vivek,
>
> Reviews should take place on the appropriate mailing list for the code being changed, not on the jdk-dev list. Please takes this to core-libs-dev.
>
> Thanks,
> David
>
> On 19/06/2018 9:52 AM, Deshpande, Vivek R wrote:
>
> Hi All
>
> Forgot to add the links:
> https://bugs.openjdk.java.net/browse/JDK-8205194 <https://bugs.openjdk.java.net/browse/JDK-8205194>
> webrev:
> http://cr.openjdk.java.net/~vdeshpande/vectorizedMismatch_jdk/webrev.0 <http://cr.openjdk.java.net/~vdeshpande/vectorizedMismatch_jdk/webrev.0>
> 0/
>
> Regards.
> Vivek
>
> From: Deshpande, Vivek R
> Sent: Monday, June 18, 2018 4:50 PM
> To: 'jdk-dev at openjdk.java.net <mailto:jdk-dev at openjdk.java.net>' <jdk-dev at openjdk.java.net <mailto:jdk-dev at openjdk.java.net>>
> Cc: 'Paul Sandoz' <paul.sandoz at oracle.com <mailto:paul.sandoz at oracle.com>>; Viswanathan, Sandhya
> <sandhya.viswanathan at intel.com <mailto:sandhya.viswanathan at intel.com>>
> Subject: RFR(S): 8205194: Improve the Array Comparison when there is a mismatch at first element.
>
> Hi All
>
> I would like to contribute a patch which improves the array comparison when there is a mismatch for the first element.
> This avoids call to vectorizedMismatch method and gives ~80x speed up.
> Please review and sponsor the patch.
>
> Regards,
> Vivek
>
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