Hi Jason,
Thanks for checking, the difference of the utf16 numbers seemed to be
just outside of the error range.
Regards, Roger
On 9/9/20 3:17 PM, Tatton, Jason wrote:
Hi Roger,
Thanks for your question. The code path for UTF16 has hasn't been interacted
with in a meaningful way in this patch so I think this is just noise. To
validate this hypothesis I re-ran the benchmark with 10 forks (default is 5),
the results indicate that the performance of the UTF16 implementation of
indexOf(char) has not been materially changed:
Without the new StringLatin1 indexOf(char) intrinsic:
Benchmark Mode Cnt Score Error Units
IndexOfBenchmark.latin1_mixed_char avgt 25 27550.832 ± 347.570 ns/op
IndexOfBenchmark.utf16_mixed_char avgt 25 18472.190 ± 219.185 ns/op
With the new StringLatin1 indexOf(char) intrinsic:
Benchmark Mode Cnt Score Error Units
IndexOfBenchmark.latin1_mixed_char avgt 5 17806.338 ± 217.399 ns/op
IndexOfBenchmark.utf16_mixed_char avgt 5 18276.366 ± 470.528 ns/op
In fact, on this run the performance of utf16 was better than without this
patch, this is however a 1% improvement which fits within the error range seen
on these tests of between 1-2%. So I think it's fair to say that this patch has
no effect on the performance of the existing StringUTF16 indexOf(char) method.
-----Original Message-----
From: core-libs-dev <core-libs-dev-r...@openjdk.java.net> On Behalf Of Roger
Riggs
Sent: 08 September 2020 15:54
To: core-libs-dev@openjdk.java.net
Subject: RE: [EXTERNAL] JDK-8173585: Intrinsify StringLatin1.indexOf(char)
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Hi Jason,
With respect to the increased ns/op in the utf16_mixed_char benchmark, how
should we understand the lower performance?
Thanks, Roger
On 9/8/20 8:02 AM, Tatton, Jason wrote:
Hi Andrew, thank you for taking the time to review this.
Since we have now moved to git, I have raised a new PR for this RFR:
https://urldefense.com/v3/__https://github.com/openjdk/jdk/pull/71__;!!GqivPVa7Brio!NewvwHYXhjOSSwNJArOOHrkBu818bCSzfDOe8hgvEM5idglmYuTub0vn0Ydzi02o$
https://bugs.openjdk.java.net/browse/JDK-8173585
I have improved the micro benchmark in the ways which you and others have
requested, namely:
+ The benchmark is now included in test/micro/org/openjdk/bench/java/lang as
StringIndexOfChar (as advised by my colleagues here at AWS; Xin Liu and Volker
Simonis).
+ Times are now in nanoseconds.
+ Terminating characters ('a') are in 66.666% of tested strings.
+ I have added four new benchmarks which operate on a random length strings (32
characters being the average) of type either StringLatin1 of StringUTF16 and
call indexOf(char) or indexOf(String).
I have included below the output of these four tests below:
Without the new StringLatin1 indexOf(char) intrinsic:
Benchmark Mode Cnt Score Error Units
IndexOfBenchmark.latin1_mixed_char avgt 5 26389.129 ± 182.581 ns/op
IndexOfBenchmark.utf16_mixed_char avgt 5 17885.383 ± 435.933 ns/op
With the new StringLatin1 indexOf(char) intrinsic:
Benchmark Mode Cnt Score Error Units
IndexOfBenchmark.latin1_mixed_char avgt 5 17875.185 ± 407.716 ns/op
IndexOfBenchmark.utf16_mixed_char avgt 5 18292.802 ± 167.306 ns/op
The objective of the patch is to bring the performance of StringLatin1
indexOf(char) in line with StringUTF16 indexOf(char) for x86 and ARM64. We can
see above that this has been achieved. Similar results were obtained when
running on ARM.
Regards,
Jason
