From: William L. I. I. <wl...@ho...> - 2002-12-19 01:38:20
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On Wed, Dec 18, 2002 at 05:20:02PM -0800, David Lang wrote: > Ok, I wasn't sure of the cause, but I've seen this as far back as 2.2 I > had a machine trying to run 2000 processes under 2.2 and 2.4.0 (after > upping the 2.2 kernel limit) and top would cost me ~40% throughput on the > machine (while claiming it was useing ~5% of the CPU) > David Lang It wasn't really lying to you. The issue is that the kernel samples at regular intervals to avoid timer reprogramming overhead. Now top(1) is isochronous in nature as it's trying to periodically refresh, and so it runs in lockstep with the clock interrupt, and the kernel hands back bad numbers to top(1). Bill |