From: Matthew Wilcox <willy@infradead.org>
To: Michal Hocko <mhocko@kernel.org>
Cc: Huaisheng Ye <yehs1@lenovo.com>,
akpm@linux-foundation.org, linux-mm@kvack.org, vbabka@suse.cz,
mgorman@techsingularity.net, pasha.tatashin@oracle.com,
alexander.levin@verizon.com, hannes@cmpxchg.org,
penguin-kernel@I-love.SAKURA.ne.jp, colyli@suse.de,
chengnt@lenovo.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] include/linux/gfp.h: use unsigned int in gfp_zone
Date: Fri, 4 May 2018 08:40:04 -0700 [thread overview]
Message-ID: <20180504154004.GB29829@bombadil.infradead.org> (raw)
In-Reply-To: <20180504133533.GR4535@dhcp22.suse.cz>
On Fri, May 04, 2018 at 03:35:33PM +0200, Michal Hocko wrote:
> On Fri 04-05-18 14:52:08, Huaisheng Ye wrote:
> > Suggest using unsigned int instead of int for bit within gfp_zone.
> > @@ -401,7 +401,7 @@ static inline bool gfpflags_allow_blocking(const gfp_t gfp_flags)
> > static inline enum zone_type gfp_zone(gfp_t flags)
> > {
> > enum zone_type z;
> > - int bit = (__force int) (flags & GFP_ZONEMASK);
> > + unsigned int bit = (__force unsigned int) (flags & GFP_ZONEMASK);
> >
> > z = (GFP_ZONE_TABLE >> (bit * GFP_ZONES_SHIFT)) &
> > ((1 << GFP_ZONES_SHIFT) - 1);
That reminds me. I wanted to talk about getting rid of GFP_ZONE_TABLE.
Instead, we should encode the zone number in the bottom three bits of
the gfp mask, while preserving the rules that ZONE_NORMAL gets encoded
as zero (so GFP_KERNEL | GFP_HIGHMEM continues to work) and also leaving
__GFP_MOVABLE in bit 3 so that it can continue to be used as a flag.
So I was thinking ...
-#define ___GFP_DMA 0x01u
-#define ___GFP_HIGHMEM 0x02u
-#define ___GFP_DMA32 0x04u
+#define ___GFP_ZONE_MASK 0x07u
#define __GFP_DMA ((__force gfp_t)OPT_ZONE_DMA ^ ZONE_NORMAL)
#define __GFP_HIGHMEM ((__force gfp_t)OPT_ZONE_HIGHMEM ^ ZONE_NORMAL)
#define __GFP_DMA32 ((__force gfp_t)OPT_ZONE_DMA32 ^ ZONE_NORMAL)
#define __GFP_MOVABLE ((__force gfp_t)ZONE_MOVABLE ^ ZONE_NORMAL | \
___GFP_MOVABLE)
#define GFP_ZONEMASK ((__force gfp_t)___GFP_ZONE_MASK | ___GFP_MOVABLE)
Then we can delete GFP_ZONE_TABLE and GFP_ZONE_BAD.
gfp_zone simply becomes:
static inline enum zone_type gfp_zone(gfp_t flags)
{
return ((__force int)flags & ___GFP_ZONE_MASK) ^ ZONE_NORMAL;
}
Huaisheng Ye, would you have time to investigate this idea?
next prev parent reply other threads:[~2018-05-04 15:40 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-04 6:52 [PATCH 0/3] Some fixes for mm code optimization Huaisheng Ye
[not found] ` <1525416729-108201-4-git-send-email-yehs1@lenovo.com>
2018-05-04 13:18 ` [PATCH 3/3] mm/page_alloc: Fix typo in debug info of calculate_node_totalpages Michal Hocko
2018-05-05 2:10 ` [External] " Huaisheng HS1 Ye
2018-05-09 7:48 ` Michal Hocko
[not found] ` <1525416729-108201-3-git-send-email-yehs1@lenovo.com>
2018-05-04 13:35 ` [PATCH 2/3] include/linux/gfp.h: use unsigned int in gfp_zone Michal Hocko
2018-05-04 15:40 ` Matthew Wilcox [this message]
2018-05-04 17:50 ` [External] " Huaisheng HS1 Ye
2018-05-06 9:32 ` Huaisheng HS1 Ye
2018-05-06 13:48 ` Matthew Wilcox
2018-05-06 16:17 ` Huaisheng HS1 Ye
2018-05-06 18:55 ` Matthew Wilcox
2018-05-07 17:16 ` Huaisheng HS1 Ye
2018-05-07 18:44 ` Matthew Wilcox
2018-05-07 21:25 ` David Sterba
2018-05-08 0:25 ` Matthew Wilcox
2018-05-09 9:36 ` David Sterba
2018-05-15 11:54 ` Matthew Wilcox
2018-05-21 17:06 ` David Sterba
2018-05-09 14:57 ` Huaisheng HS1 Ye
2018-05-08 0:25 ` Huaisheng HS1 Ye
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