[PATCH 1/2] topology/sysfs: provide drawer id and siblings attributes

Heiko Carstens
2016-06-08T09:09:34Z

The s390 cpu topology gained another hierarchy level. The top level is
now called drawer and contains several books. A book used to be the
top level.

In order to expose the cpu topology to user space allow to create new
sysfs attributes dependent on CONFIG_SCHED_DRAWER which an
architecture may define and select.

These additional attributes will be available:

/sys/devices/system/cpu/cpuX/topology/drawer_id
/sys/devices/system/cpu/cpuX/topology/drawer_siblings
/sys/devices/system/cpu/cpuX/topology/drawer_siblings_list

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
---
Documentation/cputopology.txt | 40 ++++++++++++++++++++++++++++++++--------
drivers/base/topology.c | 13 +++++++++++++
2 files changed, 45 insertions(+), 8 deletions(-)

diff --git a/Documentation/cputopology.txt b/Documentation/cputopology.txt
index 12b1b25b4da9..f722f227a73b 100644
--- a/Documentation/cputopology.txt
+++ b/Documentation/cputopology.txt
@@ -20,48 +20,70 @@ to /proc/cpuinfo output of some architectures:
identifier (rather than the kernel's). The actual value is
architecture and platform dependent.

-4) /sys/devices/system/cpu/cpuX/topology/thread_siblings:
+4) /sys/devices/system/cpu/cpuX/topology/drawer_id:
+
+ the drawer ID of cpuX. Typically it is the hardware platform's
+ identifier (rather than the kernel's). The actual value is
+ architecture and platform dependent.
+
+5) /sys/devices/system/cpu/cpuX/topology/thread_siblings:

internal kernel map of cpuX's hardware threads within the same
core as cpuX.

-5) /sys/devices/system/cpu/cpuX/topology/thread_siblings_list:
+6) /sys/devices/system/cpu/cpuX/topology/thread_siblings_list:

human-readable list of cpuX's hardware threads within the same
core as cpuX.

-6) /sys/devices/system/cpu/cpuX/topology/core_siblings:
+7) /sys/devices/system/cpu/cpuX/topology/core_siblings:

internal kernel map of cpuX's hardware threads within the same
physical_package_id.

-7) /sys/devices/system/cpu/cpuX/topology/core_siblings_list:
+8) /sys/devices/system/cpu/cpuX/topology/core_siblings_list:

human-readable list of cpuX's hardware threads within the same
physical_package_id.

-8) /sys/devices/system/cpu/cpuX/topology/book_siblings:
+9) /sys/devices/system/cpu/cpuX/topology/book_siblings:

internal kernel map of cpuX's hardware threads within the same
book_id.

-9) /sys/devices/system/cpu/cpuX/topology/book_siblings_list:
+10) /sys/devices/system/cpu/cpuX/topology/book_siblings_list:

human-readable list of cpuX's hardware threads within the same
book_id.

+11) /sys/devices/system/cpu/cpuX/topology/drawer_siblings:
+
+ internal kernel map of cpuX's hardware threads within the same
+ drawer_id.
+
+12) /sys/devices/system/cpu/cpuX/topology/drawer_siblings_list:
+
+ human-readable list of cpuX's hardware threads within the same
+ drawer_id.
+
To implement it in an architecture-neutral way, a new source file,
-drivers/base/topology.c, is to export the 6 or 9 attributes. The three book
-related sysfs files will only be created if CONFIG_SCHED_BOOK is selected.
+drivers/base/topology.c, is to export the 6 to 12 attributes. The book
+and drawer related sysfs files will only be created if CONFIG_SCHED_BOOK
+and CONFIG_SCHED_DRAWER are selected.
+
+CONFIG_SCHED_BOOK and CONFIG_DRAWER are currently only used on s390, where
+they reflect the cpu and cache hierarchy.

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_drawer_id(cpu)
#define topology_sibling_cpumask(cpu)
#define topology_core_cpumask(cpu)
#define topology_book_cpumask(cpu)
+#define topology_drawer_cpumask(cpu)

The type of **_id macros is int.
The type of **_cpumask macros is (const) struct cpumask *. The latter
@@ -78,6 +100,8 @@ not defined by include/asm-XXX/topology.h:

For architectures that don't support books (CONFIG_SCHED_BOOK) there are no
default definitions for topology_book_id() and topology_book_cpumask().
+For architectures that don't support drawes (CONFIG_SCHED_DRAWER) there are
+no default definitions for topology_drawer_id() and topology_drawer_cpumask().

Additionally, CPU topology information is provided under
/sys/devices/system/cpu and includes these files. The internal
diff --git a/drivers/base/topology.c b/drivers/base/topology.c
index 8b7d7f8e5851..df3c97cb4c99 100644
--- a/drivers/base/topology.c
+++ b/drivers/base/topology.c
@@ -77,6 +77,14 @@ static DEVICE_ATTR_RO(book_siblings);
static DEVICE_ATTR_RO(book_siblings_list);
#endif

+#ifdef CONFIG_SCHED_DRAWER
+define_id_show_func(drawer_id);
+static DEVICE_ATTR_RO(drawer_id);
+define_siblings_show_func(drawer_siblings, drawer_cpumask);
+static DEVICE_ATTR_RO(drawer_siblings);
+static DEVICE_ATTR_RO(drawer_siblings_list);
+#endif
+
static struct attribute *default_attrs[] = {
&dev_attr_physical_package_id.attr,
&dev_attr_core_id.attr,
@@ -89,6 +97,11 @@ static struct attribute *default_attrs[] = {
&dev_attr_book_siblings.attr,
&dev_attr_book_siblings_list.attr,
#endif
+#ifdef CONFIG_SCHED_DRAWER
+ &dev_attr_drawer_id.attr,
+ &dev_attr_drawer_siblings.attr,
+ &dev_attr_drawer_siblings_list.attr,
+#endif
NULL
};

--
2.6.6