In microtime(), use pushfl/popfl to preserve the interrupt enable flag instead of sti to it restore to its usual state.  pushfl/popfl is actually faster in protected mode on Pentiums (4+3 cycles instead of 9), and using sti made it extremely inconvenient to call microtime() from fast interrupt handlers.  pushfl/popfl is a couple of cycles slower than sti on 486's and a couple more cycles slower on 386's, but the relative cost of using it is not large since microtime() has to use slow i/o instructions on the old cpus.
In microtime(), use pushfl/popfl to preserve the interrupt enable flag
instead of sti to it restore to its usual state.  pushfl/popfl is
actually faster in protected mode on Pentiums (4+3 cycles instead of 9),
and using sti made it extremely inconvenient to call microtime() from
fast interrupt handlers.  pushfl/popfl is a couple of cycles slower than
sti on 486's and a couple more cycles slower on 386's, but the relative
cost of using it is not large since microtime() has to use slow i/o
instructions on the old cpus.

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