seconds, or a 7 percent improvement. That's about as good as it gets. Throughout it all, vmstat shows that disk throughput is the bottleneck.

Lessons Learned

In the preceding process we learned that disk speed is inarguably the bottleneck. This particular four−year−old SCSI disk handles data just as quickly as a modern IDE disk, but if we want faster performance we need a faster disk. Faster disks are much less expensive than a whole new machine, even if that new machine includes a faster disk.

Best of all, you can now go to your manager and say, "This is bad. We need a faster disk. Our vendor, AbsoluteBSD.com, has them for $400," and be certain of your facts. That's much better than saying, "This is bad; we need a new server."

Of course, programs other than make buildkernel have completely different requirements and must be evaluated separately. While a 5 to 10 percent increase isn'st a huge performance boost, it can make the difference between doing maintenance during the normal maintenance window and pulling a desperate triple shift to get the new equipment slammed into place so that people can do their work the next morning.

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