| Date | Fri, 26 May 2006 15:06:46 +0800 | From | Wu Fengguang <> | Subject | Re: [PATCH 04/33] readahead: page flag PG_readahead |
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On Thu, May 25, 2006 at 09:23:11AM -0700, Andrew Morton wrote: > Wu Fengguang <wfg@mail.ustc.edu.cn> wrote: > > > > An new page flag PG_readahead is introduced as a look-ahead mark, which > > reminds the caller to give the adaptive read-ahead logic a chance to do > > read-ahead ahead of time for I/O pipelining. > > > > It roughly corresponds to `ahead_start' of the stock read-ahead logic. > > > > This isn't a very revealing description of what this flag does.
Updated to:
An new page flag PG_readahead is introduced.
It acts as a look-ahead mark, which tells the page reader: Hey, it's time to invoke the adaptive read-ahead logic! For the sake of I/O pipelining, don't wait until it runs out of cached pages. ;-)
> > +#define __SetPageReadahead(page) __set_bit(PG_readahead, &(page)->flags) > > uh-oh. This is extremly risky. Needs extensive justification, please.
Ok, removed the ugly __ :-)
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