Al Boldi wrote:
Chris Snook wrote:
At best, reads can be read-ahead and cached, which is why
sequential swap-in sucks less. On-demand reads are as expensive as I/O
can get.
Which means that it should be at least as fast as swap-out, even faster
because write to disk is usually slower than read on modern disks. But
linux currently shows a distinct 2x slowdown for sequential swap-in wrt
swap-out.
That's because writes are faster than reads in moderate
quantities.
The disk caches writes, allowing the OS to write a whole
bunch of data into the disk cache and the disk can optimize
the IO a bit internally.
The same optimization is not possible for reads.
--
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the best in the world, and those who believe it already is. Each group
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