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In the summer of 1997,
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NASA's Pathfinder spacecraft landed
on the surface of Mars,
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and began transmitting incredible,
iconic images back to Earth.
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But several days in,
something went terribly wrong.
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The transmissions stopped.
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Pathfinder was, in effect,
procrastinating:
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keeping itself fully occupied
but failing to do its most important work.
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What was going on?
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There was a bug, it turned out,
in its scheduler.
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Every operating system has something
called the scheduler
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that tells the CPU how long
to work on each task before switching,
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and what to switch to.
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Done right, computers move so fluidly
between their various responsibilities,
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they give the illusion
of doing everything simultaneously.
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But we all know what happens
when things go wrong.
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This should give us, if nothing else,
some measure of consolation.
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Even computers get overwhelmed sometimes.
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Maybe learning about the computer science
of scheduling
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can give us some ideas about our own
human struggles with time.
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One of the first insights is that all
the time you spend prioritizing your work
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is time you aren't spending doing it.
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For instance, let's say when you check
your inbox, you scan all the messages,
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choosing which is the most important.
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Once you've dealt with that one,
you repeat.
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Seems sensible,
but there's a problem here.
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This is what's known
as a quadratic-time algorithm.
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With an inbox that's twice as
full, these passes will take twice as long
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and you'll need to do
twice as many of them!
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This means four times the work.
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The programmers
of the operating system Linux
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encountered a similar problem in 2003.
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Linux would rank every single
one of its tasks in order of importance,
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and sometimes spent more time
ranking tasks than doing them.
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The programmers’ counterintuitive solution
was to replace this full ranking
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with a limited number
of priority “buckets.”
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The system was less precise
about what to do next
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but more than made up for it
by spending more time making progress.
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So with your emails, insisting on always
doing the very most important thing first
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could lead to a meltdown.
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Waking up to an inbox three times fuller
than normal
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could take nine times longer to clear.
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You’d be better off replying
in chronological order, or even at random!
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Surprisingly, sometimes giving up
on doing things in the perfect order
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may be the key to getting them done.
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Another insight that emerges
from computer scheduling
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has to do with one of the most prevalent
features of modern life: interruptions.
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When a computer goes
from one task to another,
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it has to do what's called
a context switch,
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bookmarking its place in one task,
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moving old data out of its memory
and new data in.
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Each of these actions comes at a cost.
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The insight here is that there’s
a fundamental tradeoff
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between productivity and responsiveness.
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Getting serious work done
means minimizing context switches.
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But being responsive means reacting
anytime something comes up.
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These two principles
are fundamentally in tension.
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Recognizing this tension allows us
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to decide where
we want to strike that balance.
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The obvious solution
is to minimize interruptions.
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The less obvious one is to group them.
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If no notification
or email requires a response
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more urgently than once an hour, say,
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then that’s exactly how often
you should check them. No more.
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In computer science, this idea goes by
the name of interrupt coalescing.
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Rather than dealing with
things as they come up –
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Oh, the mouse was moved?
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A key was pressed?
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More of that file downloaded? –
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the system groups these
interruptions together
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based on how long they can afford to wait.
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In 2013, interrupt coalescing
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triggered a massive improvement
in laptop battery life.
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This is because deferring interruptions
lets a system check everything at once,
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then quickly re-enter a low-power state.
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As with computers, so it is with us.
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Perhaps adopting a similar approach
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might allow us users
to reclaim our own attention,
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and give us back one of the things
that feels so rare in modern life: rest.