Messages in this thread | | | Date | Sun, 17 Mar 2002 19:20:28 +0000 | From | Joel Becker <> | Subject | Re: fadvise syscall? |
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On Sun, Mar 17, 2002 at 01:41:37PM +0000, Anton Altaparmakov wrote: > When you want large data streaming, i.e. you start getting worried about > memory pressure, then you want open(2) + O_DIRECT. No caching done. Perfect > for large data streams and we have that already. I agree that you may want > some form of asynchronous read ahead with passed pages being dropped from > the cache but that could be just a open(2) + O_SEQUENTIAL (doesn't exist yet).
O_DIRECT isn't the right thing for large streaming. You want readahead and dropbehind. O_DIRECT takes substantial penalties for its lack of copy/cacheing. This works fine in certain circumstances (applications that keep their own caching), but for something like a video or mp3, you'll win with working dropbehind easily.
Joel
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