One wonders what exactly the patch author(s) has been testing so he missed an order of magnitude slowdown. It looks like the issue either shows up rarely or we've been neglecting block I/O performance for about an year.
The fix is not present in 3.2.2 and i am not finding it in Greg's 3.2.3-pre patches.
Posted Feb 4, 2012 20:49 UTC (Sat) by giraffedata (subscriber, #1954)
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Actually, I wonder what the patch author intended to accomplish (and that his testing presumably demonstrated he did). The article mentions larger less scattered I/Os, but in a situation where the queue tends to be empty, I can't see where that would accomplish anything. When I look at this change, I just see a frontal assault on doing stuff in parallel with the I/O turnaround time.