On Thu, Jun 04, 2009 at 06:23:15PM +0800, KOSAKI Motohiro wrote: > > Current linux policy is, zone_reclaim_mode is enabled by default if the > machine > has large remote node distance. it's because we could assume that large > distance > mean large server until recently. > > Unfortunately, recent modern x86 CPU (e.g. Core i7, Opeteron) have P2P > transport > memory controller. IOW it's seen as NUMA from software view. > Some Core i7 machine has large remote node distance. > > Yanmin reported zone_reclaim_mode=1 cause large apache regression. > > One Nehalem machine has 12GB memory, > but there is always 2GB free although applications accesses lots of files. > Eventually we located the root cause as zone_reclaim_mode=1. > > Actually, zone_reclaim_mode=1 mean "I dislike remote node allocation rather > than > disk access", it makes performance improvement to HPC workload. > but it makes performance degression to desktop, file server and web server. > > In general, workload depended configration shouldn't put into default > settings. > > However, current code is long standing about two year. Highest POWER and IA64 > HPC machine > (only) use this setting. > > Thus, x86 and almost rest architecture change default setting, but Only power > and ia64 > remain current configuration for backward-compatibility.
The above lines are too long. Limit to 72 cols in general could be better as git-log may add additional leading white spaces. Thank you for all the efforts! Acked-by: Wu Fengguang <fengguang...@intel.com> > Signed-off-by: KOSAKI Motohiro <kosaki.motoh...@jp.fujitsu.com> > Cc: Christoph Lameter <c...@linux-foundation.org> > Cc: Rik van Riel <r...@redhat.com> > Cc: Robin Holt <h...@sgi.com> > Cc: "Zhang, Yanmin" <yanmin.zh...@intel.com> > Cc: Wu Fengguang <fengguang...@intel.com> > Cc: linux-i...@vger.kernel.org > Cc: linuxppc-dev@ozlabs.org > --- > arch/powerpc/include/asm/topology.h | 6 ++++++ > include/linux/topology.h | 7 +------ > 2 files changed, 7 insertions(+), 6 deletions(-) > > Index: b/include/linux/topology.h > =================================================================== > --- a/include/linux/topology.h > +++ b/include/linux/topology.h > @@ -54,12 +54,7 @@ int arch_update_cpu_topology(void); > #define node_distance(from,to) ((from) == (to) ? LOCAL_DISTANCE : > REMOTE_DISTANCE) > #endif > #ifndef RECLAIM_DISTANCE > -/* > - * If the distance between nodes in a system is larger than RECLAIM_DISTANCE > - * (in whatever arch specific measurement units returned by node_distance()) > - * then switch on zone reclaim on boot. > - */ > -#define RECLAIM_DISTANCE 20 > +#define RECLAIM_DISTANCE INT_MAX > #endif > #ifndef PENALTY_FOR_NODE_WITH_CPUS > #define PENALTY_FOR_NODE_WITH_CPUS (1) > Index: b/arch/powerpc/include/asm/topology.h > =================================================================== > --- a/arch/powerpc/include/asm/topology.h > +++ b/arch/powerpc/include/asm/topology.h > @@ -10,6 +10,12 @@ struct device_node; > > #include <asm/mmzone.h> > > +/* > + * Distance above which we begin to use zone reclaim s/begin to/default to/ ? > + */ > +#define RECLAIM_DISTANCE 20 > + > + > static inline int cpu_to_node(int cpu) > { > return numa_cpu_lookup_table[cpu]; > _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev