On 4/19/18 9:51 PM, Zhengyuan Liu wrote: > Hi, Shaohua > > I found it indeed doesn't do front merge when two threads flush plug list concurrently. To > reappear , I prepared two IO threads , named a0.io and a1.io . > Thread a1.io uses libaio to write 5 requests : > sectors: 16 + 8, 40 + 8, 64 + 8, 88 + 8, 112 + 8 > Thread a0.io uses libaio to write other 5 requests : > sectors: 8+ 8, 32 + 8, 56 + 8, 80 + 8, 104 + 8 I'm cutting some of the below. Thanks for the detailed email. It's mostly on purpose that we don't spend cycles and memory on maintaining a separate front merge hash, since it's generally not something that happens very often. If you have a thread pool doing IO and split sequential IO such that you would benefit a lot from front merging, then I would generally claim that you're not writing your app in the most optimal manner. So I'm curious, what's the big interest in front merging? -- Jens Axboe
