Re: [PATCH v2] socket.7: add description for SO_BUSY_POLL
From: Michael Kerrisk (man-pages)
Date: Mon Jan 20 2014 - 11:29:05 EST
On 07/10/2013 04:18 PM, Eliezer Tamir wrote:
> Add description for the SO_BUSY_POLL socket option to the socket(7) manpage.
Long after the fact, I've applied this. Thanks, Eliezer.
Would you be willing also to write a patch for the POLL_BUSY_LOOP flag of
> fixed typos reported by Rasmus Villemoes
> Signed-off-by: Eliezer Tamir <eliezer.tamir@xxxxxxxxxxxxxxx>
> man7/socket.7 | 25 +++++++++++++++++++++++++
> 1 files changed, 25 insertions(+), 0 deletions(-)
> diff --git a/man7/socket.7 b/man7/socket.7
> index f2213eb..5edcb09 100644
> --- a/man7/socket.7
> +++ b/man7/socket.7
> @@ -694,6 +694,31 @@ for details on control messages.
> Gets the socket type as an integer (e.g.,
> .BR SOCK_STREAM ).
> This socket option is read-only.
> +.B SO_BUSY_POLL
> +Sets the approximate time in microseconds to busy poll on a blocking receive
> +when there is no data. Increasing this value requires
> +.BR CAP_NET_ADMIN .
> +The default for this option is controlled by the
> +.I /proc/sys/net/core/busy_read
> +The value in the
> +.I /proc/sys/net/core/busy_poll
> +file determines how long
> +.BR select (2)
> +.BR poll (2)
> +will busy poll when they operate on sockets with
> +.BR SO_BUSY_POLL
> +set and no events to report are found.
> +In both cases busy polling will only be done when the socket last received data
> +from a network device that supports this option.
> +While busy polling may improve latency of some applications, care must be
> +taken when using it since this will increase both CPU utilization and power usage.
> .SS Signals
> When writing onto a connection-oriented socket that has been shut down
> (by the local or the remote end)
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