Revision 494de90098784b8e2797598cefdd34188884ec2e authored by Mel Gorman on 03 July 2008, 04:27:51 UTC, committed by Linus Torvalds on 03 July 2008, 16:22:59 UTC
The non-NUMA case of build_zonelist_cache() would initialize the zlcache_ptr for both node_zonelists[] to NULL. Which is problematic, since non-NUMA only has a single node_zonelists[] entry, and trying to zero the non-existent second one just overwrote the nr_zones field instead. As kswapd uses this value to determine what reclaim work is necessary, the result is that kswapd never reclaims. This causes processes to stall frequently in low-memory situations as they always direct reclaim. This patch initialises zlcache_ptr correctly. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Tested-by: Dan Williams <dan.j.williams@intel.com> [ Simplified patch a bit ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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cputopology.txt
Export cpu topology info via sysfs. Items (attributes) are similar
to /proc/cpuinfo.
1) /sys/devices/system/cpu/cpuX/topology/physical_package_id:
represent the physical package id of cpu X;
2) /sys/devices/system/cpu/cpuX/topology/core_id:
represent the cpu core id to cpu X;
3) /sys/devices/system/cpu/cpuX/topology/thread_siblings:
represent the thread siblings to cpu X in the same core;
4) /sys/devices/system/cpu/cpuX/topology/core_siblings:
represent the thread siblings to cpu X in the same physical package;
To implement it in an architecture-neutral way, a new source file,
drivers/base/topology.c, is to export the 4 attributes.
If one architecture wants to support this feature, it just needs to
implement 4 defines, typically in file include/asm-XXX/topology.h.
The 4 defines are:
#define topology_physical_package_id(cpu)
#define topology_core_id(cpu)
#define topology_thread_siblings(cpu)
#define topology_core_siblings(cpu)
The type of **_id is int.
The type of siblings is cpumask_t.
To be consistent on all architectures, the 4 attributes should have
default values if their values are unavailable. Below is the rule.
1) physical_package_id: If cpu has no physical package id, -1 is the
default value.
2) core_id: If cpu doesn't support multi-core, its core id is 0.
3) thread_siblings: Just include itself, if the cpu doesn't support
HT/multi-thread.
4) core_siblings: Just include itself, if the cpu doesn't support
multi-core and HT/Multi-thread.
So be careful when declaring the 4 defines in include/asm-XXX/topology.h.
If an attribute isn't defined on an architecture, it won't be exported.
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