This small sample of settings have collectively made a huge difference on the systems I manage.
in /etc/fstab ------------------- mount all systems noatime mount filesystems other than /boot /root with data=writeback
This one is dangerous is there is any likelihood of your machine crashing unexpectedly, e.g. power cuts, children pulling plugs, tripping over wires. If you're going to do it, measure the performance change and see if you are prepared to live with the risk. Check the other things first, like making sure that DMA is enabled on your disks.
Turning off atime will break some programs. You'll often find cron jobs that clean up files that haven't been read in a while. If the atime isn't updated then that won't work. When debugging programs that are supposed to be reading configuration files and don't appear to be, then it's useful to do an "ls -lu" to see if the file has in fact been read -- with noatime this won't work either. "noatime" is useful for file systems that are very busy (e.g. a large message store) that doesn't depend upon needing to know the access time, ever. You do need to be careful with this one though and unless you have a very busy disk subsystem it's not worth the effort. For most users, you're unlikely to see a positive benefit from this one -- users that will see a difference are on the edge of what their machine is capable of, if not slightly beyond it.
in /etc/syslog.conf ------------------------ change logging to asynchronous:
*.info;mail.none;authpriv.none;cron.none -/var/log/messages
authpriv.* -/var/log/secure
mail.* -/var/log/maillog
I can't see this making a big difference unless you're doing a heck of a lot of logging. If you're doing that much logging, then you have more serious fish to fry. By "a lot" I mean megabytes per hour.
in /etc/sysctl.conf --------------------------- net.ipv4.tcp_sack =0 net.ipv4.tcp_timestamps =0 net.ipv4.tcp_window_scaling =0 net.ipv4.tcp_fin_timeout = 30 net.ipv4.tcp_keepalive_time =1800
I can't comment on these, but reducing the keepalive time from two hours to half an hour doesn't look like a performance improvement, although it can work around connection timeouts in some state-full routers.
in /etc/nsswitch.conf ------------------------------- passwd: files shadow: files group: files
[etc] Not convinced. Deleting the extras will only make a difference if you're looking up stuff that doesn't exist. This does happen from time to time, and the affected commands (netstat, iptables, lsof, etc) provide a switch to turn lookup off -- in general it doesn't make any difference though.
in /etc/profile ---------------- export LANG=en_US
This actually is quite a big one. Not a lot of use to me in the UK, and not a lot of use to someone in, say, France. Basically, if you turn off UTF-8 then a lot of commands will run a lot faster -- grep is the one that springs to mind most. If you look through the start-up scripts, you'll see lots of places where UTF-8 processing is turned off. If you've got a modern machine (mine is a 2.2GHz P4, only slightly obsolete :-)) then you won't notice unless you're grepping a gigabyte of data.
jch
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