Messages in this thread | | | Date | Wed, 18 Mar 2009 13:21:30 -0400 (EDT) | From | Christoph Lameter <> | Subject | Re: [PATCH 24/27] Convert gfp_zone() to use a table of precalculated values |
| |
> time. > > > > > const int gfp_zone_table[GFP_ZONEMASK] = { > > > > ZONE_NORMAL, /* 00 No flags set */ > > > > ZONE_DMA, /* 01 Only GFP_DMA set */ > > > > ZONE_HIGHMEM, /* 02 Only GFP_HIGHMEM set */ > > > > ZONE_DMA, /* 03 GFP_HIGHMEM and GFP_DMA set */ > > > > ZONE_DMA32, /* 04 Only GFP_DMA32 set */ > > > > ZONE_DMA, /* 05 GFP_DMA and GFP_DMA32 set */ > > > > ZONE_DMA32, /* 06 GFP_DMA32 and GFP_HIGHMEM set */ > > > > ZONE_DMA, /* 07 GFP_DMA, GFP_DMA32 and GFP_DMA32 set */ > > > > ZONE_MOVABLE, /* 08 Only ZONE_MOVABLE set */ > > > > ZONE_DMA, /* 09 MOVABLE + DMA */ > > > > ZONE_MOVABLE, /* 0A MOVABLE + HIGHMEM */ > > > > ZONE_DMA, /* 0B MOVABLE + DMA + HIGHMEM */ > > > > ZONE_DMA32, /* 0C MOVABLE + DMA32 */ > > > > ZONE_DMA, /* 0D MOVABLE + DMA + DMA32 */ > > > > ZONE_DMA32, /* 0E MOVABLE + DMA32 + HIGHMEM */ > > > > ZONE_DMA /* 0F MOVABLE + DMA32 + HIGHMEM + DMA > > > > }; > > > > > > > > Hmmmm... Guess one would need to add some #ifdeffery here to setup > > > > ZONE_NORMAL in cases there is no DMA, DMA32 and HIGHMEM. > > > > > > > > > > Indeed, as I said, this is somewhat error prone which is why the patch > > > calculates the table at run-time instead of compile-time trickery. > > > > One would need to define some macros to make it simpler I guess > > > > Write something like > > > > #ifdef CONFIG_ZONE_DMA > > #define TZONE_DMA ZONE_DMA > > #else > > #define TZONE_DMA ZONE_NORMAL > > #endif > > > > for each configurable item. Then just add the T to the above table. > > > > If you don't mind, I'd like to postpone writing such a patch until a second > or third pass at improving the allocator. I don't think I'll have the time > in the short-term to put together a const-initialised-table patch that will > definitily be correct. > > Alternatively, I can drop this patch entirely from the set. > >
Let me give it a shot:
Note that there is a slight buggyness in the current implementation of gfp_zone. If you set both GFP_DMA32 and GFP_HIGHMEM and the arch does not support GFP_DMA32 then gfp_zone returns GFP_HIGHMEM which may result in memory being allocated that cannot be used for I/O.
This version here returns GFP_NORMAL which is more correct.
#ifdef CONFIG_ZONE_HIGHMEM #define OPT_ZONE_HIGHMEM ZONE_HIGHMEM #else #define OPT_ZONE_HIGHMEM ZONE_NORMAL #endif
#ifdef CONFIG_ZONE_DMA #define OPT_ZONE_DMA ZONE_DMA #else #define OPT_ZONE_DMA ZONE_NORMAL #endif
#ifdef CONFIG_ZONE_DMA32 #define OPT_ZONE_DMA32 ZONE_DMA32 #else #define OPT_ZONE_DMA32 OPT_ZONE_DMA #endif
const int gfp_zone_table[GFP_ZONEMASK] = { ZONE_NORMAL, /* 00 No flags set */ OPT_ZONE_DMA, /* 01 GFP_DMA */ OPT_ZONE_HIGHMEM, /* 02 GFP_HIGHMEM */ OPT_ZONE_DMA, /* 03 GFP_HIGHMEM GFP_DMA */ OPT_ZONE_DMA32, /* 04 GFP_DMA32 */ OPT_ZONE_DMA, /* 05 GFP_DMA32 GFP_DMA */ OPT_ZONE_DMA32, /* 06 GFP_DMA32 GFP_HIGHMEM */ OPT_ZONE_DMA, /* 07 GFP_DMA32 GFP_HIGHMEM GFP_DMA */ ZONE_NORMAL, /* 08 ZONE_MOVABLE */ OPT_ZONE_DMA, /* 09 MOVABLE + DMA */ ZONE_MOVABLE, /* 0A MOVABLE + HIGHMEM */ OPT_ZONE_DMA, /* 0B MOVABLE + HIGHMEM + DMA */ OPT_ZONE_DMA32, /* 0C MOVABLE + DMA32 */ OPT_ZONE_DMA, /* 0D MOVABLE + DMA32 + DMA */ OPT_ZONE_DMA32, /* 0E MOVABLE + DMA32 + HIGHMEM */ OPT_ZONE_DMA /* 0F MOVABLE + DMA32 + HIGHMEM + DMA */ };
| |