sysctl is a mechanism for controlling options and limits in the Unix-like operating system kernels. Sysctls can be used to tune performance or change behaviors of many subsystems.

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Improving TCP performance over a gigabit network with lots of connections and high traffic of small packets

I’m trying to improve my TCP throughput over a “gigabit network with lots of connections and high traffic of small packets”. My server OS is Ubuntu 11.10 Server 64bit. There are about 50.000 (and ...
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4answers
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After reboot debian box ignore sysctl.conf values

Where is right place for sysctl redefined values? I have: > uname -a Linux note 3.1.0-1-amd64 #1 SMP Tue Jan 10 05:01:58 UTC 2012 x86_64 GNU/Linux > cat /etc/debian_version wheezy/sid ...
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1answer
518 views

ipv6 max_addresses in sysctl.conf (Debian 6)

I'd like to assign any number of IPv6 addresses to a Debian 6 host, but I see the following setting, and want to know what are the consquences of setting higher, or does this setting approach limits ...
7
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2answers
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Postgresql Performance - Adjusting SHMMAX and SHMALL

I've read just about everything there is online about improving postgres performance, but the "right" values for SHMMAX and SHMALL still elude me. The consensus seems to be SHMMAX = total_memory/4 ...
1
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1answer
2k views

net.ipv6.conf.all.forwarding = 1 is an unknown key

I have few system with ipv6 addresses. I want to forward request from one system to another. hence I kept the option net.ipv6.conf.all.forwarding = 1 in sysctl.conf but the request is not getting ...
1
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2answers
9k views

error: “net.ipv4.netfilter.ip_conntrack_max” is an unknown key

I have a problem on Ubuntu 10.04.3 LTS x64 with sysctl net.ipv4.netfilter.ip_conntrack_max . If I run this command on shell, I get back an error: error: net.ipv4.netfilter.ip_conntrack_max" is an ...
0
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1answer
4k views

sysctl setting for maximum connections from ip address

Is there any settings in sysctl that controls the maximum number of connections that are allowed from any one ip address? I'm having connection issues a redis server and a rabbitmq instance and I'd ...
2
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1answer
1k views

Optimize linux for serving http static content

What would be the system tunables to enhance serving static content? Like increase/decrease swappines, how to max out disk caching and so on...
6
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3answers
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What does tcp_orphan_retries set to 0 mean?

Does setting tcp_orphan_retries to 0 mean there is no limit to retries, or does it mean that it won't retry at all?
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3answers
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sysctl.conf not running on boot

At what point is sysctl.conf supposed to be read during boot, and why might it not be running? I have the following settings which are not being applied when I reboot: ...
1
vote
1answer
956 views

Is there a location of the sysctl kernel parameters for osX?

I would like to read up on os X kernel parameters. I can find them listed, but where can I find the meaning of them? For example this parameter net.alf.loglevel: 55 which are not in the man ...
0
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1answer
2k views

error: “net.netfilter.nf_conntrack_acct” is an unknown key

I have the this error when I run sysctl -p in Debian 5.0.8. error: "net.netfilter.nf_conntrack_acct" is an unknown key My sysctl configuration net.netfilter.nf_conntrack_acct = 1 ...
1
vote
4answers
7k views

Persistent changes to /proc/sys/sunrpc/tcp_slot_table_entries

I'm trying to make a persistent change to sunrpc.tcp_slot_table_entries on a Linux CentOS 5.5. This value has been found important for the performance of our NFS clients, and must be set before the ...
0
votes
1answer
2k views

Tuning TCP sysctl on centos

I have website that gets higher tcp timeouts at peak times and slows down bit, here are few stat graphs http://i.stack.imgur.com/dgVyO.png sysctl config atm: net.ipv4.ip_forward = 0 ...
2
votes
2answers
3k views

How to make setting of kern.ipc.somaxconn persistent?

Want to rise value of kern.ipc.somaxconn With sysctl works ok $ sudo sysctl kern.ipc.somaxconn=2048 $ kern.ipc.somaxconn: 128 -> 2048 check it: $ sysctl -a|grep somaxconn ...
5
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3answers
5k views

Persisting nf_conntrack_max Across Reboots

In /proc I have two entries for nf_conntrack_max: /proc/sys/net/netfilter/nf_conntrack_max /proc/sys/net/nf_conntrack_max The seem to point to the same value as changing one also changes the ...
1
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1answer
5k views

Sysctl config for high performance, large activity

We have some server with a huge amount of visitors (every minute, every day). Basically we had a nice fine-tuned sysctl config for this purpose. (If you don't modify it, it starts to behave ...
3
votes
1answer
2k views

Increasing FreeBSD threads

For network apps that create one thread per connection (like Pound), threadcount can become a bottleneck on the number of concurrent connections you can server. I'm running FreeBSD 8 x64: $ sysctl ...
1
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1answer
2k views

File-descriptors setting on /etc/sysctl.conf

I have recently learnt that to be able to increase the amount of virtualhosts that we can serve via Apache depends on file-descriptors. they say the value should be added to /etc/sysctl.conf as ...
1
vote
1answer
857 views

net.inet.tcp.blackhole option on Fedora

This link of freebsdblog.org suggests a configuration option for FreeBSD that tells the system to drop all packages arriving from the network to a closed port and thus somewhat securing your system ...
111
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4answers
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FreeBSD performance tuning: Sysctl parameter, loader.conf, kernel

I wanted to share knowledge of tuning FreeBSD via sysctl.conf / loader.conf / KENCONF / etc. It was initially based on Igor Sysoev's (author of nginx) presentation about FreeBSD tuning up to ...