The eviction pass called a file freshly used only when its last-access stamp was later than the
pass's own clock. A hit stamped just before the pass began but committed after its SELECT, or
stamped by a clock that had stepped back (the test VM's does), read as old, and the file the user
had just asked for was evicted. The pass now keeps the stamp its SELECT saw and skips a file
whose stamp changed since.
peter
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