Posted Aug 30, 2010 16:01 UTC (Mon) by giraffedata
In reply to: sreadahead
Parent article: LinuxCon: A tale of two bootcharts
On a solid-state block device, where order doesn't matter, what is the point of sreadahead? The only advantage I know to reading stuff into cache ahead of time is that you can do it in optimal order.
With disk drives, I don't think user space should be ordering the reads -- that expertise belongs in the block layer and below. All you have to do is pile all the read requests into the block layer and it will order them properly (of course, you don't have to get everything in the queue at once -- eliminating 99% of the seek time is fine).
And though I don't know what the state of implementation is, in theory you shouldn't be piling anything explicitly into the block layer either; you should just be advising the block layer of your plans to read that stuff later (madvise).
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