Problem with HT support in 5.4

Jacob S stormspotter at 6Texans.net
Fri May 27 06:54:49 PDT 2005


Hello list,

I upgraded a few 5.3 servers to 5.4 yesterday and everything seemed to
go well. After booting the new kernel, dmesg correctly showed 2 logical
cpus (1 xeon with HT). 

However, when I look at top's output, it always shows at least 50% cpu
idle time - even when the load is above 10. To confirm this, I ran
burnP6 from the cpuburn port - even with over a hundred apache processes
going, exim running and a few other things, top still reported the cpu
as 50% idle. The 'C' column in top, between 'State' and 'Time' also
shows everything as being run on cpu 0. 

`ps ax | grep cpu` reports this:
 11  ??  RL     0:00.00 [idle: cpu1]
 12  ??  RL   931:45.24 [idle: cpu0]
108  ??  DL     0:04.02 [schedcpu]

So it looks like smp support is enabled and it sees the HT enabled
processor, but it's not using the second logical cpu. Is there something
I missed in compiling the kernel, or is this a bug? I have confirmed it
on two 5.4 servers now.

TIA,
Jacob


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