* [PATCH] tcp.7: Document removal of TCP_SYNQ_HSIZE
@ 2015-03-12 7:15 Peter Adkins
[not found] ` <CAA7vvKmzVsKmma=w5Lwx6ujjCcfgSsKSqt1DGEzfjb9naujkVA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
0 siblings, 1 reply; 2+ messages in thread
From: Peter Adkins @ 2015-03-12 7:15 UTC (permalink / raw)
To: mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w; +Cc: linux-man-u79uwXL29TY76Z2rM5mHXA
Hello there,
Looking over the man page for 'tcp' I came across a reference to
tuning the 'TCP_SYNQ_HSIZE' parameter when increasing
'tcp_max_syn_backlog' above 1024. However, this static sizing was
removed back in Linux 2.6.20 in favour of dynamic scaling - as part of
commit 72a3effaf633bcae9034b7e176bdbd78d64a71db.
I have included a patch below with reference to this commit, and that
the process detailed is not required on >= Linux 2.6.20. This is my
first patch for a man page, as well as groff, so I apologize if
anything is incorrect. If so, please let me know and I will resolve
and resubmit.
This patch was prepared against the current HEAD - at time of writing
- from the Kernel.org man-page repository
(f6d086878485f63e390d10f59b6beae7b96c4120), which looks to be version
3.82.
---
man7/tcp.7 | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/man7/tcp.7 b/man7/tcp.7
index 5723bde..794c636 100644
--- a/man7/tcp.7
+++ b/man7/tcp.7
@@ -530,12 +530,16 @@ The default value of 256 is increased to
1024 when the memory present in the system is adequate or
greater (>= 128Mb), and reduced to 128 for those systems with
very low memory (<= 32Mb).
-It is recommended that if this
-needs to be increased above 1024, TCP_SYNQ_HSIZE in
+
+Prior to Linux 2.6.20,
+.\" commit 72a3effaf633bcae9034b7e176bdbd78d64a71db
+it was recommended that if this needed to be increased above 1024,
+the size of the SYNACK hash table (TCP_SYNQ_HSIZE) in
.I include/net/tcp.h
be modified to keep
TCP_SYNQ_HSIZE*16<=tcp_max_syn_backlog, and the kernel be
-recompiled.
+recompiled. In Linux 2.6.20, the fixed sized TCP_SYNQ_HSIZE was removed
+in favour of dynamic sizing.
.TP
.IR tcp_max_tw_buckets " (integer; default: see below; since Linux 2.4)"
.\" Since 2.3.41
--
1.9.1
Thank you for your time.
Regards,
Peter Adkins
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^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] tcp.7: Document removal of TCP_SYNQ_HSIZE
[not found] ` <CAA7vvKmzVsKmma=w5Lwx6ujjCcfgSsKSqt1DGEzfjb9naujkVA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
@ 2015-03-22 18:45 ` Michael Kerrisk (man-pages)
0 siblings, 0 replies; 2+ messages in thread
From: Michael Kerrisk (man-pages) @ 2015-03-22 18:45 UTC (permalink / raw)
To: Peter Adkins
Cc: mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w, linux-man-u79uwXL29TY76Z2rM5mHXA
On 03/12/2015 08:15 AM, Peter Adkins wrote:
> Hello there,
>
> Looking over the man page for 'tcp' I came across a reference to
> tuning the 'TCP_SYNQ_HSIZE' parameter when increasing
> 'tcp_max_syn_backlog' above 1024. However, this static sizing was
> removed back in Linux 2.6.20 in favour of dynamic scaling - as part of
> commit 72a3effaf633bcae9034b7e176bdbd78d64a71db.
>
> I have included a patch below with reference to this commit, and that
> the process detailed is not required on >= Linux 2.6.20. This is my
> first patch for a man page, as well as groff, so I apologize if
> anything is incorrect. If so, please let me know and I will resolve
> and resubmit.
>
> This patch was prepared against the current HEAD - at time of writing
> - from the Kernel.org man-page repository
> (f6d086878485f63e390d10f59b6beae7b96c4120), which looks to be version
> 3.82.
Thanks, Peter! Applied.
Cheers,
Michael
> ---
> man7/tcp.7 | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/man7/tcp.7 b/man7/tcp.7
> index 5723bde..794c636 100644
> --- a/man7/tcp.7
> +++ b/man7/tcp.7
> @@ -530,12 +530,16 @@ The default value of 256 is increased to
> 1024 when the memory present in the system is adequate or
> greater (>= 128Mb), and reduced to 128 for those systems with
> very low memory (<= 32Mb).
> -It is recommended that if this
> -needs to be increased above 1024, TCP_SYNQ_HSIZE in
> +
> +Prior to Linux 2.6.20,
> +.\" commit 72a3effaf633bcae9034b7e176bdbd78d64a71db
> +it was recommended that if this needed to be increased above 1024,
> +the size of the SYNACK hash table (TCP_SYNQ_HSIZE) in
> .I include/net/tcp.h
> be modified to keep
> TCP_SYNQ_HSIZE*16<=tcp_max_syn_backlog, and the kernel be
> -recompiled.
> +recompiled. In Linux 2.6.20, the fixed sized TCP_SYNQ_HSIZE was removed
> +in favour of dynamic sizing.
> .TP
> .IR tcp_max_tw_buckets " (integer; default: see below; since Linux 2.4)"
> .\" Since 2.3.41
>
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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2015-03-12 7:15 [PATCH] tcp.7: Document removal of TCP_SYNQ_HSIZE Peter Adkins
[not found] ` <CAA7vvKmzVsKmma=w5Lwx6ujjCcfgSsKSqt1DGEzfjb9naujkVA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-03-22 18:45 ` Michael Kerrisk (man-pages)
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