On 2013-12-09 19:57, Saso Kiselkov wrote:
Right, but how could this result in >2x the performance? As indicated
by your diagram, you are doing at most 2 reads at once (or, you are
getting at most 1 read "for free" while the CPU is busy processing the
last block). You claimed a 10-20x speedup (I am assuming that "several"
means 3).
As I said, I'm gonna have to recheck, it's possible I might be
remembering stuff incorrectly. However, currently my possibilities for
performance testing are somewhat limited. I'll get back to you as soon
as I have more info.
Speaking from the theoretical peanut gallery, the SSDs' modern
speediness is due to their amount of NAND chips, each doing some
20MB/s or so (figures non-authoritative). So if multiple queued
tasks land on different chips - and there are dozens of them now -
it may indeed be much faster than single-chip single-requests.
The device can indeed issue operations to the chips in parallel
and return answers as they come into its buffers. Maybe so...
HTH,
//Jim
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