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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Higher rmem_max value leading to more packet loss

The rmem_max Linux setting defines the size of the buffer that receives UDP packets. When traffic becomes too busy, packet loss starts occurring. I made a graph showing how packet loss increases ...
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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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Shared memory: shmget fails: No space left on device — how to increase limits?

I call shmget many times in my program, to get shm of of average size 85840 bytes. I obtain about 32771 shm ok, then shmget doesn't return a shm, but the error: "No space left on device". I have ...
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Set sysctl.conf parameters with Puppet

This was a breeze in CFEngine... But I'm in a Puppet environment now, and need to be able to assign/ensure/check certain sysctl.conf variables. In the CFEngine world, I could simply check for specific ...
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432 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 ...
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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 ...
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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 ...
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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: ...
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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 ...
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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...
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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 ...
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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 ...