How do i view / enable kernel logs on centos / red hat linux? [duplicate]

You can see the most recent lines of output from the kernel with the dmesg command.

Otherwise, you need to ensure that

1. klogd is running (it's normally started with syslog, at boot time), and that

2. syslogd is configured to log kernel messages to a file, perhaps with the following line from /etc/syslog.conf:

   kern.*<TAB><TAB><TAB>/var/log/kernel

make sure the file /var/log/kernel exists, and restart syslogd.

You're tuning a performance setting -- you really want to be looking at performance counters, not log messages. Presumably you're increasing the number of concurrent connections to improve the performance of some application; you should keep an eye on your app.