SMP & CPU_SUSP_HLT

From: RMH <rmhlldr_at_yahoo.co.uk>
Date: Sat, 21 Jun 2003 02:47:42 +0100 (BST)
Hello gentlemen,

it seems CPU_SUSP_HLT does nothing for SMP kernels.

i386/i386/machdep.c:

#ifdef SMP
static int      cpu_idle_hlt = 0;
#else
static int      cpu_idle_hlt = 1;
#endif

It's noted that when enabled it will result in about 4.2%
loss in performance while doing buildworld. I haven't
checked with that, but I tested single-threaded applications
to suffer for about 2%, what shouldn't be a big difference.

Beyond power consumption, suspend on HLT may solve some
overheating issues common for multiprocessor systems. At
least, it does so in my case.

I suggest to remove #ifdef SMP, and place a warning into
NOTES. Let people decide.

---
Regards,
 Rhett


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Received on Fri Jun 20 2003 - 16:47:43 UTC

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