Re: [PATCH] tcp.7: Document removal of TCP_SYNQ_HSIZE
From: Michael Kerrisk (man-pages) <hidden>
Date: 2015-03-22 18:45:11
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
quoted hunk
--- 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
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