Messages in this thread |  | | Subject | Re: Linux 2.2.18: /proc/apm slows system time (was: Linux 2.2.19pre3) | Date | Sat, 30 Dec 2000 17:01:27 +0000 (GMT) | From | Alan Cox <> |
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> However, reading from /proc/apm triggers BIOS calls which involve > certain action, maybe switching to Real Mode and other things, and I > suspect that either IRQs are still disabled while the BIOS is called or > the BIOS plays bad games which Linux would have to compensate for. :-/
Looking at the one laptop with this problem I could acquire access to it seems that the box switches to SMM mode with interrupts disabled for several timer ticks. During this time the i2c bus is active and it appears to be having a slow polled conversation with the battery or something attached to the battery and monitoring it.
Doing
while { true } do cat /proc/apm done
made the box visibly stall and jerk doing X operations
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