throughput-performance: s390x sysctl settings

bz #619377 kernel: Process scheduler tuning recommendation for s390

tune-profiles/throughput-performance/sysctl.s390x.ktune

@@ -0,0 +1,40 @@
+# ktune sysctl settings for rhel6 servers, maximizing i/o throughput
+#
+# Minimal preemption granularity for CPU-bound tasks:
+# (default: 1 msec#  (1 + ilog(ncpus)), units: nanoseconds)
+kernel.sched_min_granularity_ns = 10000000
+
+# SCHED_OTHER wake-up granularity.
+# (default: 1 msec#  (1 + ilog(ncpus)), units: nanoseconds)
+#
+# This option delays the preemption effects of decoupled workloads
+# and reduces their over-scheduling. Synchronous workloads will still
+# have immediate wakeup/sleep latencies.
+kernel.sched_wakeup_granularity_ns = 15000000
+
+# TODO: this bits need comment
+kernel.sched_latency_ns = 80000000
+kernel.sched_features = 15834234
+kernel.sched_tunable_scaling = 0
+
+# If a workload mostly uses anonymous memory and it hits this limit, the entire
+# working set is buffered for I/O, and any more write buffering would require
+# swapping, so it's time to throttle writes until I/O can catch up.  Workloads
+# that mostly use file mappings may be able to use even higher values.
+#
+# The generator of dirty data starts writeback at this percentage (system default
+# is 20%)
+vm.dirty_ratio = 40
+
+# Start background writeback (via writeback threads) at this percentage (system
+# default is 10%)
+#vm.dirty_background_ratio = 15
+
+# PID allocation wrap value.  When the kernel's next PID value
+# reaches this value, it wraps back to a minimum PID value.
+# PIDs of value pid_max or larger are not allocated.
+#
+# A suggested value for pid_max is 1024 * <# of cpu cores/threads in system>
+# e.g., a box with 32 cpus, the default of 32768 is reasonable, for 64 cpus,
+# 65536, for 4096 cpus, 4194304 (which is the upper limit possible).
+#kernel.pid_max = 65536