Optimizing Linux Performance

• Phillip G. Ezolt
• Prentice Hall
• 0131486829

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I found a lot to like here, but I do need to complain about a few things. We'll do the good stuff first: there's excellent attention to detail often overlooked in performance books, the explanations are clear and illuminating, and the case studies are well done and quite interesting.

Too often a book like this will show a tool like vmstat, explain part of the output, and simply ignore the more esoteric or less interesting parts of the data. This can leave the reader wondering what certain headers mean, and send them scrambling to the man page. All too often the man page comes up short also, or gives a terse explanation that really isn't helpful. This book does better than most in that regard. I'd always like too see more, but this did fill in some gaps that man pages and other books don't bother with.

There's good attention given to explaining the relationships of data. For example, the author points out that if the number of context switches are much more than the number of timer interrupts, this must be because of sleeps or I/O waits. That's "obvious", but is easily lost in the confusion of looking at too many things at once.

The case studies are excellent, but concentrate on bugs or code optimizations rather than true system optimization. I liked that there was this kind of case study, because these often are not shown in performance books, but I wished that the author had included kernel and file system tuning studies also.

One minor annoyance cropped up throughout. When showing command line examples, the author has his prompt set to the machine name and directory, so you'll see something like this:

[ezolt@scrffy manuscript]$ sar -w -c -q 1 2

As he runs commands on different machines, the next example might be:

[root@wintermute root]# opcontrol --vmlinux=/boot/vmlinux-2.4.22-1.2174.nptlsmp

Those changing prompts distracted my eyes and often momentarily confused me. I think it's best to stick to plain "#" and "$" in examples.

I would have also appreciated a little better typography. The major chapter section headings are in a larger font, but after that everything blends together. So you get something like this:

2.2.1 vmstat (Virtual Memory Statistics)

(text ..)

2.2.1.1 CPU Performance Related Options

(text ..)

2.2.1.2 Example Usage

(text ..)

2.2.2 top (v. 2.0.x)

(text ..)

2.2.2.1 CPU Performance Related Options

(text ..)

2.2.2.2 Example Usage

(text ..)

This uniformity makes it hard to go back and quickly find the beginning of a section.

Overall, I liked this and think it will find a permanent spot in my bookcase.

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