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Perf: Improve perf of SqlDateTimeToDateTime#912

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cheenamalhotra merged 6 commits intodotnet:mainfrom
Wraith2:perf15-fasterdatetime
Apr 9, 2021
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Perf: Improve perf of SqlDateTimeToDateTime#912
cheenamalhotra merged 6 commits intodotnet:mainfrom
Wraith2:perf15-fasterdatetime

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@Wraith2
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@Wraith2 Wraith2 commented Feb 14, 2021 •
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While reviewing #853 I did some digging into the related code and profiling. The function used to convert sql date times to .net datetimes came up as hot so I tinkered with it a bit. The most important part is to avoid creating a datetime just to get a constant value from it, hardcode it instead.

Gist of the benchmark code is here: https://gist.github.com/Wraith2/d0d220f07e640c17daeb9db2d446aaa4

results:

BenchmarkDotNet=v0.12.1, OS=Windows 10.0.19042
Intel Core i9-9900K CPU 3.60GHz (Coffee Lake), 1 CPU, 16 logical and 8 physical cores
.NET Core SDK=5.0.200-preview.21079.7
  [Host]     : .NET Core 3.1.12 (CoreCLR 4.700.21.6504, CoreFX 4.700.21.6905), X64 RyuJIT
  DefaultJob : .NET Core 3.1.12 (CoreCLR 4.700.21.6504, CoreFX 4.700.21.6905), X64 RyuJIT
Method Mean Error StdDev Ratio
Original 271.50 ms 4.619 ms 4.321 ms 1.00
New 82.45 ms 0.232 ms 0.206 ms 0.30

/cc @bjornbouetsmith who this may interest

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cheenamalhotra commented Feb 16, 2021

Seems thr's a test failure you may want to take a look:

System.OverflowException : SqlDateTime overflow. Must be between 1/1/1753 12:00:00 AM and 12/31/9999 11:59:59 PM.
...
   at Microsoft.Data.SqlClient.ManualTesting.Tests.DateTimeTest.ReaderParameterTest() 
... ManualTests\SQL\DateTimeTest\DateTimeTest.cs:line 188

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Wraith2 commented Feb 16, 2021

Nice catch. Didn't see it among the other CI failures.
Reworked slightly to deal with the bounds and I've added a uint range check trick that wasn't worth using before (regressed it by 4%) but now does seem worthwhile. The range checks work by knowing that negative integers cast to extremely large positive uints so if we do zero based checks we only have to check 0 to max and not a min check.

Method Mean Error StdDev Ratio
Original 258.05 ms 2.267 ms 2.010 ms 1.00
New 85.68 ms 0.589 ms 0.551 ms 0.33

@Wraith2 Wraith2 force-pushed the perf15-fasterdatetime branch from db49342 to 1ebe544 Compare March 5, 2021 00:59
Base automatically changed from master to main March 15, 2021 17:54
@cheenamalhotra cheenamalhotra added this to the 3.0.0-preview2 milestone Mar 18, 2021
@cheenamalhotra cheenamalhotra added the Performance 📈 Issues that are targeted to performance improvements. label Mar 31, 2021
@cheenamalhotra cheenamalhotra merged commit 9853429 into dotnet:main Apr 9, 2021
@Wraith2 Wraith2 deleted the perf15-fasterdatetime branch April 15, 2021 00:41
@Wraith2 Wraith2 mentioned this pull request Jul 23, 2022
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@cheenamalhotra cheenamalhotra cheenamalhotra approved these changes

@JRahnama JRahnama Awaiting requested review from JRahnama

@johnnypham johnnypham Awaiting requested review from johnnypham

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@DavoudEshtehari DavoudEshtehari DavoudEshtehari approved these changes

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