Re: [PATCH] Writeback page range hint

[Andrew Morton]

Dave Jones <davej@xxxxxxxxxx> wrote:
>
> On Mon, Aug 23, 2004 at 06:14:00PM -0700, Andrew Morton wrote:
> 
>  > >   > +	int nonblocking:1;		/* Don't get stuck on request queues */
>  > >   > +	int encountered_congestion:1;	/* An output: a queue is full */
>  > >   > +	int for_kupdate:1;		/* A kupdate writeback */
>  > >   > +	int for_reclaim:1;		/* Invoked from the page allocator */
>  > > 
>  > >  Causes sparse spew..
>  > > 
>  > >  include/linux/writeback.h:54:19: warning: dubious one-bit signed bitfield
>  > >  include/linux/writeback.h:55:30: warning: dubious one-bit signed bitfield
>  > >  include/linux/writeback.h:56:19: warning: dubious one-bit signed bitfield
>  > >  include/linux/writeback.h:57:19: warning: dubious one-bit signed bitfield
>  > 
>  > That's fussy of it.  I assume this shuts it up?
> 
> very likely (its 2am, and I'm feeling too lazy to check).

That's the middle of the working day.

> though, is there any real reason why they are bitfields at all ?

That should have been in the changelog.  Bad Suparna.

These structures are allocated on the stack in the (deep) writeback paths. 
Saving a few bytes there does seem to be worth the increased code size.

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