Hi Yuanchu,
On Tue, Nov 19, 2024 at 08:52:14PM -0800, Yuanchu Xie wrote:
> POSIX_FADV_NOREUSE is now supported in Linux.
> Update text regarding former no op behavior. Indicate the readahead policy
> and treatment of file pages read with this flag.
>
> Link:
> Signed-off-by: T.J. Alumbaugh
> Signed-off-by: Yuanchu Xie
Thanks! I've applied the patch. I've also added Yu's Acked-by.
Have a lovely day!
Alex
> ---
> Changelog
> v5 -> v6
> - Fixed wordiness
> - Clarified LRU to mean the kernel page replacement algorithm
>
> v4 -> v5
> - Remove unnecessary changes
> - Use two space inter-sentence spacing
> - Fix lines exceeding 80-column
>
> v3 -> v4
> - Use semantic newlines
> - Format with macros like .B instead of inline \f
>
> v3: https://lore.kernel.org/linux-man/20230320222057.1976956-1-talumbau@google.com/
> v4: https://lore.kernel.org/linux-man/20241113031654.3964740-1-yuanchu@google.com/
> v5: https://lore.kernel.org/linux-man/20241114012233.4152152-1-yuanchu@google.com/
>
> man/man2/posix_fadvise.2 | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/man/man2/posix_fadvise.2 b/man/man2/posix_fadvise.2
> index ed40b0c0d..894a0762c 100644
> --- a/man/man2/posix_fadvise.2
> +++ b/man/man2/posix_fadvise.2
> @@ -64,7 +64,13 @@ The specified data will be accessed only once.
> .IP
> Before Linux 2.6.18, \fBPOSIX_FADV_NOREUSE\fP had the
> same semantics as \fBPOSIX_FADV_WILLNEED\fP.
> -This was probably a bug; since Linux 2.6.18, this flag is a no-op.
> +This was probably a bug;
> +from Linux 2.6.18 until Linux 6.2 this flag was a no-op.
> +Since Linux 6.3,
> +.B POSIX_FADV_NOREUSE
> +signals that the kernel page replacement algorithm
> +can ignore access to mapped page cache marked by this flag.
> +This is useful, for example, while streaming large files.
> .TP
> .B POSIX_FADV_WILLNEED
> The specified data will be accessed in the near future.
> @@ -130,6 +136,8 @@ in this case.)
> Under Linux, \fBPOSIX_FADV_NORMAL\fP sets the readahead window to the
> default size for the backing device; \fBPOSIX_FADV_SEQUENTIAL\fP doubles
> this size, and \fBPOSIX_FADV_RANDOM\fP disables file readahead entirely.
> +.B POSIX_FADV_NOREUSE
> +does not modify the readahead window size.
> These changes affect the entire file, not just the specified region
> (but other open file handles to the same file are unaffected).
> .SS C library/kernel differences
> --
> 2.46.0
>
--