Linux Tuning Tricks?

Milo_Mindbender writes: "Over the weekend I was attempting to improve my CD ripping performance and discovered RedHat 7.2 was running my Ultra/ATA 100 hard drive in a very slow non-DMA mode. After a fair amount of searching for how to fix this, a trivial change (look here) improved drive performance from 3MBs to 38MBs! FSCK on my 40gb partition went from over 5 minutes to under 1! This issue wasn't documented in RedHat's manuals but it effected a number of boxes in our office so I'm betting many other people in the world have the same problem. This made me wonder how many other common Linux tuning snafus there might be that a lot of people are probably missing. Do you know of any?"

Comments

Check for interrupt clashes, and test

[Mark Wilkinson]

We recently built a machine around an Abit VP6 with 5 hard disks on it (three on the main IDE controller, 2 on the HighPoint 370 secondary controller). After a few days I noticed we were getting bad blocks on the drives on the HighPoint controller. Running badblocks on the disks gave random errors all over the place.

I then noticed that the Ethernet card was being given the same IRQ as the IDE controller and got suspicious. I swapped the ether card into different PCI slots until it got its own IRQ, then ran the badblocks check again. Everything ran clean.

It's also entertaining to use lmbench to test your hardware: it can plot pretty graphs showing how the IO speed changes across the disk surface so you can decide where to put your partitions, if that's important to you.

Main point though: if at all possible tune your hardware and then test using badblocks, lmbench and such before you put the machine into production (or when you've got a solid backup). As the article says, problems with your disk subsystem can loose lots of information quickly.

Distributing software but not knowledge = problem

[tshoppa]

While Redhat is pretty good at making a distribution that boots and installs on a very wide number of machines, it's not so good at making this distribution be high-performance. Many things are set to the safest possible value (like the OP's IDE DMA modes) when a much more reasonable value would work on 99% of the hardware out there.

Life is made more difficult because there is buggy and/or broken hardware out there. I don't blame Redhat for accomodating this hardware, but by doing so they are making their distribution more complicated and less useful for those "in the know".

Redhat also, of course, distributes the non-kernel binaries optimized for Intel 80386 CPU's when the vast vast majority of installs are going on Pentium-class or better machines. And it doesn't help any that Redhat is using and distributing a very nonstandard version of GCC; see what the GCC developers say about such branches and what application developers say about this branch.

To actually learn a lot about Linux and all the associated tools that make it work, I highly recommend the Linux From Scratch method: build everything from source! You can optimize the build to your machine and end up with not only better performance, but a vastly superior knowledge of everything that used to be "under the hood".

"Tabilize".... Or just use plain text.

[Bob_Robertson]

I agree that wide tables are annoying, but HTML viewers (and printers) nicely re-wrap plain text to fit.

Sooooo much easier than tables is just to use preformatted text.

Just a side comment from someone who has always written his web page in vi.

Bob-