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prioritize sendfile over splice since it results in fewer context switches when sending to pipes

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splice returns to userspace when the pipe is full, sendfile
just blocks until it's done, this can achieve much higher throughput
This commit is contained in:
The8472 2020-09-06 22:47:58 +02:00
parent 67a6059aa5
commit cd3bddc044
1 changed files with 16 additions and 16 deletions
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32
library/std/src/io/copy.rs
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@ -173,22 +173,6 @@ mod kernel_copy {
)
.map(|bytes_copied| bytes_copied + bytes_flushed)
}
(CopyParams(reader_meta, Some(readfd)), CopyParams(writer_meta, Some(writefd)))
if reader_meta.is_fifo() || writer_meta.is_fifo() =>
{
// splice
let bytes_flushed = flush()?;
let max_write = reader.min_limit();
let (mut reader, mut writer) =
unsafe { (fd_as_file(readfd), fd_as_file(writefd)) };
crate::sys::fs::sendfile_splice(
crate::sys::fs::SpliceMode::Splice,
&mut reader,
&mut writer,
max_write,
)
.map(|bytes_sent| bytes_sent + bytes_flushed)
}
(
CopyParams(FdMeta::Metadata(reader_meta), Some(readfd)),
CopyParams(_, Some(writefd)),
@ -208,6 +192,22 @@ mod kernel_copy {
)
.map(|bytes_sent| bytes_sent + bytes_flushed)
}
(CopyParams(reader_meta, Some(readfd)), CopyParams(writer_meta, Some(writefd)))
if reader_meta.is_fifo() || writer_meta.is_fifo() =>
{
// splice
let bytes_flushed = flush()?;
let max_write = reader.min_limit();
let (mut reader, mut writer) =
unsafe { (fd_as_file(readfd), fd_as_file(writefd)) };
crate::sys::fs::sendfile_splice(
crate::sys::fs::SpliceMode::Splice,
&mut reader,
&mut writer,
max_write,
)
.map(|bytes_sent| bytes_sent + bytes_flushed)
}
_ => super::generic_copy(reader, writer),
}
}