Hi, On a dual SMP box running SuSE-2.4.19-79 (United Linux rc4), the boot time in /proc/stat can vary 1 second when read. I haven't seen this on a UP box. Its not a major issue, but I guess its a hindrance if one's expecting it to never change: gen2 12:06:52 ~: grep btime /proc/stat btime 1046838984 gen2 12:07:06 ~: grep btime /proc/stat btime 1046838984 gen2 12:07:07 ~: grep btime /proc/stat btime 1046838983 gen2 12:07:07 ~: grep btime /proc/stat btime 1046838983 gen2 12:07:08 ~: grep btime /proc/stat btime 1046838983 gen2 12:07:09 ~: grep btime /proc/stat btime 1046838984 gen2 12:07:10 ~: grep btime /proc/stat btime 1046838984 gen2 12:07:11 ~: grep btime /proc/stat btime 1046838983 I'm not familiar with the way IO-APIC timers work or the interrupt timer itself, so can someone explain why this is the case? I'm guessing that it might simply be a timing issue between when the actual interrupt handling updating jiffies in do_timer and the bottom half updating xtime.tv_sec (see kernel/timer.c). Maybe by caching the btime value so that its only calculated once is the way to go. Attached is the suggested fix, as well as the output from /proc/cpuinfo & /proc/interrupts. If someone could get back to me on this it would be much appreciated. Thanks, -- Kingsley