b3aeaf2ed1
clobbers this variable. Long ago, when the idle loop wasn't in a process, it set switchtime.tv_sec to zero to indicate that the time needs to be read after the idle loop finishes. The special case for this isn't needed now that there is an idle process (for each CPU). The time is read in the normal way when the idle process is switched away from. The seconds component of the time is only zero for the first second after the uptime is set, and the mostly-dead code was only executed during this time. (This was slightly broken by using uptimes instead of times relative to the Epoch -- in the original version the seconds component of the time was only 0 for the first second after the Epoch.) In mi_switch(), moved the setting of switchticks to just after the first (and now only) setting of switchtime. This setting used to be delayed since a late setting was needed for the idle case and an early setting was not needed. Now the early setting is needed so that fork_exit() doesn't need to set either switchtime or switchticks. Removed now-completely-rotted comment attached to this. Most of the code described by the comment had already moved to sched_switch().
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