Messages in this thread | | | Date | Sun, 26 Aug 2001 04:57:46 +0200 | From | < ( Marc) (A.) (Lehmann )> | Subject | Re: [resent PATCH] Re: very slow parallel read performance |
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On Sat, Aug 25, 2001 at 11:02:25PM -0300, Rik van Riel <riel@conectiva.com.br> wrote: > This is because the readahead windows are too large so the > kernel ends up evicting data before its needed and has to > re-read the data. > > Also see http://linux-mm.org/wiki/moin.cgi/StreamingIo > in the Linux-MM wiki.
O_STREAMING is an interesting idea (I talked with stefan traby about the problem and we came to a similar conclusion - fadvise instead of madvise, and per-file characteristics as opposed to blockdevices or global settings).
Anyway, so far it really looks as if this is the case - there is some limit (around 700 conns) where the available memory doesn't suffice for read-ahead.
> This problem should be relatively easy to fix for 2.4.
Nice ;)
-- -----==- | ----==-- _ | ---==---(_)__ __ ____ __ Marc Lehmann +-- --==---/ / _ \/ // /\ \/ / pcg@goof.com |e| -=====/_/_//_/\_,_/ /_/\_\ XX11-RIPE --+ The choice of a GNU generation | | - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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