Messages in this thread | | | Subject | Re: [PATCH 7/7] readahead: basic support of interleaved reads | From | Rusty Russell <> | Date | Sat, 21 Jul 2007 17:24:39 +1000 |
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On Sat, 2007-07-21 at 12:43 +0800, Fengguang Wu wrote: > plain text document attachment (readahead-interleaved-reads.patch) > This is a simplified version of the pagecache context based readahead. > It handles the case of multiple threads reading on the same fd and invalidating > each others' readahead state. It does the trick by scanning the pagecache and > recovering the current read stream's readahead status. > > The algorithm works in a opportunistic way, in that it do not try to detect > interleaved reads _actively_, which requires a probe into the page cache(which > means a little more overheads for random reads). It only tries to handle a > previously started sequential readahead whose state was overwritten by > another concurrent stream, and it can do this job pretty well.
Hi Fengguang,
This is really clever!
Only one slight complaint: I wonder if "radix_tree_scan_hole" could be expressed as "radix_tree_extent_size" which return the number of populated indices up to "max_scan". Returning a length seems more intuitive to me (and I think gets rid of the wraparound error case?)
Cheers, Rusty.
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