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2015-08-07s390/numa: make core to node mapping data dynamicMichael Holzheu
The core to node mapping data consumes about 2 KB bss data. To save memory for the non-NUMA case, make the data dynamic. In addition change the "core_to_node" array from "int" to "s32" which saves 1 KB also for the NUMA case. Suggested-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2015-08-07s390/topology: remove topology lockMichael Holzheu
Since we are already protected by the "sched_domains_mutex" lock, we can safely remove the topology lock. Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2015-08-04s390/numa: add emulation supportMichael Holzheu
NUMA emulation (aka fake NUMA) distributes the available memory to nodes without using real topology information about the physical memory of the machine. Splitting the system memory into nodes replicates the memory management structures for each node. Particularly each node has its own "mm locks" and its own "kswapd" task. For large systems, under certain conditions, this results in improved system performance and/or latency based on reduced pressure on the mm locks and the kswapd tasks. NUMA emulation distributes CPUs to nodes while respecting the original machine topology information. This is done by trying to avoid to separate CPUs which reside on the same book or even on the same MC. Because the current Linux scheduler code requires a stable cpu to node mapping, cores are pinned to nodes when the first CPU thread is set online. This patch is based on the initial implementation from Philipp Hachtmann. Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2015-08-03s390/numa: add topology tree infrastructurePhilipp Hachtmann
NUMA emulation needs proper means to mangle the book/mc/core topology of the machine. The topology tree (toptree) consistently maintains cpu masks for the root, each node, and all leaves of the tree while the user may use the toptree functions to rearrange the tree in various ways. This patch contains several changes from Michael Holzheu. Signed-off-by: Philipp Hachtmann <phacht@linux.vnet.ibm.com> Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2015-08-03s390/numa: add core infrastructurePhilipp Hachtmann
Enable core NUMA support for s390 and add one simple default mode "plain" that creates one single NUMA node. This patch contains several changes from Michael Holzheu. Signed-off-by: Philipp Hachtmann <phacht@linux.vnet.ibm.com> Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>