avoid ReadFile syscall if we know that there is nothing to read from file#56387
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adamsitnik merged 2 commits intodotnet:mainfrom Jul 27, 2021
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Tagging subscribers to this area: @dotnet/area-system-io Issue DetailsThis can save us a single while (await fileStream.ReadAsync(userBuffer, cancellationToken) != 0)The perf gain depends on the file size and the number of actual reads. For a small file where we read entire content with first call, we can save up to 10%.
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stephentoub
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Jul 27, 2021
src/libraries/System.Private.CoreLib/src/System/IO/Strategies/AsyncWindowsFileStreamStrategy.cs
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Co-authored-by: Stephen Toub <stoub@microsoft.com>
This was referenced Jul 28, 2021
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This can save us a single
ReadFilesys-call for cases when we know that there is nothing to read from the file, which should happen once for every loop like this:The perf gain depends on the file size and the number of actual reads. For a small file where we read entire content with first call, we can save up to 10%.