| Message ID | 20090226112431.GA25330@kryten (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Commit | c2fdf3a9b2d52842808a8e551b53b55dd9b45030 |
| Delegated to: | Benjamin Herrenschmidt |
| Headers | show |
From: Anton Blanchard <anton@samba.org> Date: Thu, 26 Feb 2009 22:24:32 +1100 > On PowerPC we allocate large boot time hashes on node 0. This leads to > an imbalance in the free memory, for example on a 64GB box (4 x 16GB > nodes): > > Free memory: > Node 0: 97.03% > Node 1: 98.54% > Node 2: 98.42% > Node 3: 98.53% > > If we switch to using vmalloc (like ia64 and x86-64) things are more > balanced: > > Free memory: > Node 0: 97.53% > Node 1: 98.35% > Node 2: 98.33% > Node 3: 98.33% > > For many HPC applications we are limited by the free available memory on > the smallest node, so even though the same amount of memory is used the > better balancing helps. > > Since all 64bit NUMA capable architectures should have sufficient > vmalloc space, it makes sense to enable it via CONFIG_64BIT. > > Signed-off-by: Anton Blanchard <anton@samba.org> Acked-by: David S. Miller <davem@davemloft.net>
On Thu, 2009-02-26 at 22:24 +1100, Anton Blanchard wrote: > Hi David, > > > Hmmm... my bad, I think you need to keep the CONFIG_NUMA > > there too as there is a TLB usage penalty for non-NUMA > > systems if you only use CONFIG_64BIT there. > > Sorry that was my screwup, here's a fixed version. Sounds good, how do we proceed for merging that ? Andrew ? Should it hop by linux-mm ? Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> --- > Anton > > -- > > On PowerPC we allocate large boot time hashes on node 0. This leads to > an imbalance in the free memory, for example on a 64GB box (4 x 16GB > nodes): > > Free memory: > Node 0: 97.03% > Node 1: 98.54% > Node 2: 98.42% > Node 3: 98.53% > > If we switch to using vmalloc (like ia64 and x86-64) things are more > balanced: > > Free memory: > Node 0: 97.53% > Node 1: 98.35% > Node 2: 98.33% > Node 3: 98.33% > > For many HPC applications we are limited by the free available memory on > the smallest node, so even though the same amount of memory is used the > better balancing helps. > > Since all 64bit NUMA capable architectures should have sufficient > vmalloc space, it makes sense to enable it via CONFIG_64BIT. > > Signed-off-by: Anton Blanchard <anton@samba.org> > --- > > diff --git a/include/linux/bootmem.h b/include/linux/bootmem.h > index 95837bf..0c4d4b7 100644 > --- a/include/linux/bootmem.h > +++ b/include/linux/bootmem.h > @@ -144,10 +144,10 @@ extern void *alloc_large_system_hash(const char *tablename, > > #define HASH_EARLY 0x00000001 /* Allocating during early boot? */ > > -/* Only NUMA needs hash distribution. > - * IA64 and x86_64 have sufficient vmalloc space. > +/* Only NUMA needs hash distribution. 64bit NUMA architectures have > + * sufficient vmalloc space. > */ > -#if defined(CONFIG_NUMA) && (defined(CONFIG_IA64) || defined(CONFIG_X86_64)) > +#if defined(CONFIG_NUMA) && defined(CONFIG_64BIT) > #define HASHDIST_DEFAULT 1 > #else > #define HASHDIST_DEFAULT 0 > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@ozlabs.org > https://ozlabs.org/mailman/listinfo/linuxppc-dev
diff --git a/include/linux/bootmem.h b/include/linux/bootmem.h index 95837bf..0c4d4b7 100644 --- a/include/linux/bootmem.h +++ b/include/linux/bootmem.h @@ -144,10 +144,10 @@ extern void *alloc_large_system_hash(const char *tablename, #define HASH_EARLY 0x00000001 /* Allocating during early boot? */ -/* Only NUMA needs hash distribution. - * IA64 and x86_64 have sufficient vmalloc space. +/* Only NUMA needs hash distribution. 64bit NUMA architectures have + * sufficient vmalloc space. */ -#if defined(CONFIG_NUMA) && (defined(CONFIG_IA64) || defined(CONFIG_X86_64)) +#if defined(CONFIG_NUMA) && defined(CONFIG_64BIT) #define HASHDIST_DEFAULT 1 #else #define HASHDIST_DEFAULT 0