Re: [patch] mm: clean up zone flags

[Mel Gorman <mgorman@suse.de>]

On Tue, Sep 02, 2014 at 06:26:53PM -0400, Johannes Weiner wrote:
> From 2420ad16df0634e073ad327f0f72472d9b03762b Mon Sep 17 00:00:00 2001
> From: Johannes Weiner <hannes@cmpxchg.org>
> Date: Tue, 2 Sep 2014 10:14:36 -0400
> Subject: [patch] mm: clean up zone flags
> 
> Page reclaim tests zone_is_reclaim_dirty(), but the site that actually
> sets this state does zone_set_flag(zone, ZONE_TAIL_LRU_DIRTY), sending
> the reader through layers indirection just to track down a simple bit.
> 
> Remove all zone flag wrappers and just use bitops against zone->flags
> directly.  It's just as readable and the lines are barely any longer.
> 
> Also rename ZONE_TAIL_LRU_DIRTY to ZONE_DIRTY to match ZONE_WRITEBACK,
> and remove the zone_flags_t typedef.
> 
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
> Acked-by: David Rientjes <rientjes@google.com>

I would have gone with making them ZONE_TAIL_DIRTY and ZONE_TAIL_WRITEBACK
because to me it's clearer what the flag means.  ZONE_DIRTY can be
interpreted as "the zone has dirty pages" which is not what reclaim
cares about, it cares about dirty pages at the tail of the LRU.  However,
I don't feel strongly enough to make a big deal about it so

Acked-by: Mel Gorman <mgorman@suse.de>

Thanks.

-- 
Mel Gorman
SUSE Labs

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