Documentation: create new scheduler/ subdirectory

The top-level Documentation/ directory is unmanageably large, so we
should take any obvious opportunities to move stuff into subdirectories.
These sched-*.txt files seem an obvious easy case.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 70 deletions

diff --git a/Documentation/sched-domains.txt b/Documentation/sched-domains.txt
deleted file mode 100644
index a9e990ab980f..000000000000
--- a/Documentation/sched-domains.txt
+++ /dev/null
@@ -1,70 +0,0 @@
-Each CPU has a "base" scheduling domain (struct sched_domain). These are
-accessed via cpu_sched_domain(i) and this_sched_domain() macros. The domain
-hierarchy is built from these base domains via the ->parent pointer. ->parent
-MUST be NULL terminated, and domain structures should be per-CPU as they
-are locklessly updated.
-
-Each scheduling domain spans a number of CPUs (stored in the ->span field).
-A domain's span MUST be a superset of it child's span (this restriction could
-be relaxed if the need arises), and a base domain for CPU i MUST span at least
-i. The top domain for each CPU will generally span all CPUs in the system
-although strictly it doesn't have to, but this could lead to a case where some
-CPUs will never be given tasks to run unless the CPUs allowed mask is
-explicitly set. A sched domain's span means "balance process load among these
-CPUs".
-
-Each scheduling domain must have one or more CPU groups (struct sched_group)
-which are organised as a circular one way linked list from the ->groups
-pointer. The union of cpumasks of these groups MUST be the same as the
-domain's span. The intersection of cpumasks from any two of these groups
-MUST be the empty set. The group pointed to by the ->groups pointer MUST
-contain the CPU to which the domain belongs. Groups may be shared among
-CPUs as they contain read only data after they have been set up.
-
-Balancing within a sched domain occurs between groups. That is, each group
-is treated as one entity. The load of a group is defined as the sum of the
-load of each of its member CPUs, and only when the load of a group becomes
-out of balance are tasks moved between groups.
-
-In kernel/sched.c, rebalance_tick is run periodically on each CPU. This
-function takes its CPU's base sched domain and checks to see if has reached
-its rebalance interval. If so, then it will run load_balance on that domain.
-rebalance_tick then checks the parent sched_domain (if it exists), and the
-parent of the parent and so forth.
-
-*** Implementing sched domains ***
-The "base" domain will "span" the first level of the hierarchy. In the case
-of SMT, you'll span all siblings of the physical CPU, with each group being
-a single virtual CPU.
-
-In SMP, the parent of the base domain will span all physical CPUs in the
-node. Each group being a single physical CPU. Then with NUMA, the parent
-of the SMP domain will span the entire machine, with each group having the
-cpumask of a node. Or, you could do multi-level NUMA or Opteron, for example,
-might have just one domain covering its one NUMA level.
-
-The implementor should read comments in include/linux/sched.h:
-struct sched_domain fields, SD_FLAG_*, SD_*_INIT to get an idea of
-the specifics and what to tune.
-
-For SMT, the architecture must define CONFIG_SCHED_SMT and provide a
-cpumask_t cpu_sibling_map[NR_CPUS], where cpu_sibling_map[i] is the mask of
-all "i"'s siblings as well as "i" itself.
-
-Architectures may retain the regular override the default SD_*_INIT flags
-while using the generic domain builder in kernel/sched.c if they wish to
-retain the traditional SMT->SMP->NUMA topology (or some subset of that). This
-can be done by #define'ing ARCH_HASH_SCHED_TUNE.
-
-Alternatively, the architecture may completely override the generic domain
-builder by #define'ing ARCH_HASH_SCHED_DOMAIN, and exporting your
-arch_init_sched_domains function. This function will attach domains to all
-CPUs using cpu_attach_domain.
-
-Implementors should change the line
-#undef SCHED_DOMAIN_DEBUG
-to
-#define SCHED_DOMAIN_DEBUG
-in kernel/sched.c as this enables an error checking parse of the sched domains
-which should catch most possible errors (described above). It also prints out
-the domain structure in a visual format.