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Old 10-12-2009, 12:33 PM   #1
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Registered: Mar 2006
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Can't edit backlog

Hello, i want to increase backlog-queue from 1024 to 2048. I run this command via ssh access

[root@server ~]# sysctl -w net.ipv4.tcp_max_syn_backlog="2048"
error: "Operation not permitted" setting key "net.ipv4.tcp_max_syn_backlog"
And i edit via File Manager ( HyperVm with Centos5 )
/proc /sys /net /ipv4 / tcp_max_syn_backlog

Unable to change value from 1024 to 2048

Anyone please help me to change this ... Thank you.
Old 09-23-2010, 06:19 PM   #2
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Please note that in order to change tcp_max_syn_backlog to a larger value, you might also have to change TCP_SYNQ_HSIZE defined in tcp.h (which would require a kernel recompile). For more info on tcp_max_syn_backlog and other TCP variables, check this link out.
Note that although the document covers the 2.4.x Linux Kernels, I've double checked the article for accuracy.

On my CentOS5.x system, I found TCP_SYNQ_HSIZE here;
#define TCP_SYNQ_HSIZE          512     /* Size of SYNACK hash table */
We also have a thread here in LQ that covers RHEL-based kernel compiling (CentOS is based on RHEL).


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