Messages in this thread | | | From | Daniel Phillips <> | Subject | Re: [resent PATCH] Re: very slow parallel read performance | Date | Sun, 26 Aug 2001 18:54:55 +0200 |
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On August 25, 2001 01:23 am, pcg@goof.com ( Marc) (A.) (Lehmann ) wrote: > I could imagine that read() executes, returns to > userspace and at the same time the kernel thinks "nothing to do, let's > readahead". While, in the concurrent case, there is hardly a time when no > read() is running. But read-ahead does not seem to work that way.
But it's a very interesting idea: instead of performing readahead in generic_file_read the user thread would calculate the readahead window information and pass it off to a kernel thread dedicated to readahead. This thread can make an informed, global decision on how much IO to submit. The user thread benefits by avoiding some stalls due to readahead->readpage, as well as avoiding thrashing due to excessive readahead.
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