Message-ID: <3C23BF4B.70BDABBE@marxmeier.com>
Date: Sat, 22 Dec 2001 00:01:31 +0100
From: Michael Marxmeier <mike@marxmeier.com>
Organization: Marxmeier Software AG
MIME-Version: 1.0
To: lkml <linux-kernel@vger.kernel.org>
Subject: Question on sys_readahead()
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Sender: linux-kernel-owner@vger.kernel.org

I have a question on sys_readahead and would appreciate 
some hint or a pointer.

- When was this call added?

- As far as i understand the code it reads the data into 
  the page cache. The data is ready sync and there is no
  way to do this async and have a notification unless using
  a separate thread.

A typical use i could see is preloading some data in the
page cache from a separate thread (eg. for a media player).

BTW: AFAICS the code is off by one if offset/count is not in 
PAGE_SIZE chunks? 

  unsigned long start = offset >> PAGE_CACHE_SHIFT;
  unsigned long len = (count + ((long)offset & ~PAGE_CACHE_MASK)) >> PAGE_CACHE_SHIFT;


Thanks
Michael

-- 
Michael Marxmeier           Marxmeier Software AG
E-Mail: mike@marxmeier.com  Besenbruchstrasse 9
Phone : +49 202 2431440     42285 Wuppertal, Germany
Fax   : +49 202 2431420     http://www.marxmeier.com/
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