Messages in this thread |  | | Date | Mon, 30 Oct 2000 17:35:49 +0100 | From | Martin Dalecki <> | Subject | Re: PATCH: killing read_ahead[] |
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Linus Torvalds wrote: > > On Wed, 25 Oct 2000, Rik van Riel wrote: > > > > OTOH, block-dev readahead makes sense for filesystems where > > the packing locality is close to the access pattern BUT NOT > > close to anything the page cache would recognise as being > > close. > > I dunno. The main reason I'd like to get the block devices into the page > cache is that right now there is no way to mmap them - something that can > potentially be _very_ useful, regardless of readahead. > > And quite frankly, the generic file readahead has been pounded upon and > tested a lot more than the block device read-ahead ever was. I bet it > performs better if for no other reason.
And then of course the FS is the LOGICAL level of access to the device - so if read ahead matters then it's this level where it should happen - since this is the place where actual predictability of the next access (actually the assumption that the access will happen at least semi-sequentially) has good chances to be right. So you are completely right that the page-cache is the right place where the rahead logic should take place. I have just filled the argumentation gap ;-).
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