Re: [resent PATCH] Re: very slow parallel read performance

From: Marc (pcg@goof.com)
Date: Sat Aug 25 2001 - 21:57:46 EST


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/



This archive was generated by hypermail 2b29 : Fri Aug 31 2001 - 21:00:19 EST