Messages in this thread | | | Date | Tue, 2 May 2006 16:20:10 +0800 | From | Wu Fengguang <> | Subject | Re: [RFC] kernel facilities for cache prefetching |
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On Tue, May 02, 2006 at 10:09:36AM +0200, Jens Axboe wrote: > I tried something very similar to this years ago, except I made it > explicit instead of hiding it in the blk_run_backing_dev() which we > didn't have at that time. My initial results showed that you would get a > load of requests for different pages so would end up doing io randomly > instead again.
Yes, the hard one would be _not_ to impact normal I/Os in any way. A simple solution for the case of deadline scheduler would be:
- static const int read_expire = HZ / 2; /* max time before a read is submitted. */ + static const int read_expire = HZ / 2; /* max time before a impending read is submitted. */ + static const int reada_expire = HZ * 30; /* max time before a read-ahead is submitted. */
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