Re: [PATCH/RFC] Simplified Readahead

From: Steven Pratt
Date: Fri Sep 24 2004 - 11:58:49 EST


Nick Piggin wrote:

Steven Pratt wrote:

Andrew Morton wrote:

Steven Pratt <slpratt@xxxxxxxxxxxxxx> wrote:


would like to offer up an alternative simplified design which will not only make the code easier to maintain,


We won't know that until all functionality is in place.

Ok, but both you and Nick indicated that the queue congestion isn't needed,

I would have thought that always doing the readahead would provide a
more graceful degradation, assuming the readahead algorithm is fairly
accurate, and copes with things like readahead thrashing (which we
hope is the case).

Yes, that is exactly my thought. I think this is what the new code does.


I do think we should skip the I/O for POSIX_FADV_WILLNEED against a
congested queue. I can't immediately think of a good reason for skipping
the I/O for normal readahead.


I don't see why you should skip the readahead for FADVISE_WILLNEED
either. Presumably if someone needs this, they really need it. We
should aim for optimal behaviour when the apis are being used correctly...

Ok, great, since this is what it does.

Thanks, Steve


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