aboutsummaryrefslogtreecommitdiff
path: root/Documentation/cputopology.txt
diff options
context:
space:
mode:
authorHeiko Carstens <heiko.carstens@de.ibm.com>2010-08-31 10:28:17 +0200
committerIngo Molnar <mingo@elte.hu>2010-09-09 20:41:25 +0200
commitb40d8ed4e42c79f8ed1cf345eed0888f4a2f0678 (patch)
treee7bfe98c1cbf21a871fee2c25640898c7b60bcfb /Documentation/cputopology.txt
parent01a08546af311c065f34727787dd0cc8dc0c216f (diff)
downloadlinux-linaro-android-b40d8ed4e42c79f8ed1cf345eed0888f4a2f0678.tar.gz
topology/sysfs: Provide book id and siblings attributes
Create attributes: /sys/devices/system/cpu/cpuX/topology/book_id /sys/devices/system/cpu/cpuX/topology/book_siblings which show the book id and the book siblings of a cpu. Unlike the attributes for SMT and MC these attributes are only present if CONFIG_SCHED_BOOK is set. There is no reason to pollute sysfs for every architecture with unused attributes. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <20100831082844.435648457@de.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'Documentation/cputopology.txt')
-rw-r--r--Documentation/cputopology.txt23
1 files changed, 20 insertions, 3 deletions
diff --git a/Documentation/cputopology.txt b/Documentation/cputopology.txt
index f1c5c4bccd3..902d3151f52 100644
--- a/Documentation/cputopology.txt
+++ b/Documentation/cputopology.txt
@@ -14,25 +14,39 @@ to /proc/cpuinfo.
identifier (rather than the kernel's). The actual value is
architecture and platform dependent.
-3) /sys/devices/system/cpu/cpuX/topology/thread_siblings:
+3) /sys/devices/system/cpu/cpuX/topology/book_id:
+
+ the book ID of cpuX. Typically it is the hardware platform's
+ identifier (rather than the kernel's). The actual value is
+ architecture and platform dependent.
+
+4) /sys/devices/system/cpu/cpuX/topology/thread_siblings:
internel kernel map of cpuX's hardware threads within the same
core as cpuX
-4) /sys/devices/system/cpu/cpuX/topology/core_siblings:
+5) /sys/devices/system/cpu/cpuX/topology/core_siblings:
internal kernel map of cpuX's hardware threads within the same
physical_package_id.
+6) /sys/devices/system/cpu/cpuX/topology/book_siblings:
+
+ internal kernel map of cpuX's hardware threads within the same
+ book_id.
+
To implement it in an architecture-neutral way, a new source file,
-drivers/base/topology.c, is to export the 4 attributes.
+drivers/base/topology.c, is to export the 4 or 6 attributes. The two book
+related sysfs files will only be created if CONFIG_SCHED_BOOK is selected.
For an architecture to support this feature, it must define some of
these macros in include/asm-XXX/topology.h:
#define topology_physical_package_id(cpu)
#define topology_core_id(cpu)
+#define topology_book_id(cpu)
#define topology_thread_cpumask(cpu)
#define topology_core_cpumask(cpu)
+#define topology_book_cpumask(cpu)
The type of **_id is int.
The type of siblings is (const) struct cpumask *.
@@ -45,6 +59,9 @@ not defined by include/asm-XXX/topology.h:
3) thread_siblings: just the given CPU
4) core_siblings: just the given CPU
+For architectures that don't support books (CONFIG_SCHED_BOOK) there are no
+default definitions for topology_book_id() and topology_book_cpumask().
+
Additionally, CPU topology information is provided under
/sys/devices/system/cpu and includes these files. The internal
source for the output is in brackets ("[]").