Re: [libvirt] [PATCH] node_memory: Add new parameter field to tune the new sysfs knob

Upstream kernel introduced new sysfs knob "merge_across_nodes" to specify if pages from different numa nodes can be merged. When set to 0, only pages which physically reside in the memory area of same NUMA node can be merged. When set to 1, pages from all nodes can be merged. This patch supports the tuning by adding new param field "shm-merge-across-nodes".

--- Perhaps two bool options like "--disable-shm-merge-across-nodes", and "--enable-shm-merge-across-nodes" are good, but could the kernel sysfs knob have other values beyond 0 and 1 in future?

+++ b/include/libvirt/libvirt.h.in @@ -4489,6 +4489,16 @@ typedef virMemoryParameter *virMemoryParameterPtr; */ # define VIR_NODE_MEMORY_SHARED_FULL_SCANS "shm_full_scans" +/* VIR_NODE_MEMORY_SHARED_MERGE_ACROSS_NODES: + * + * Macro for typed parameter that represents whether pages from + * different NUMA nodes can be merged, when its value is 0, only + * pages which physically reside in the memory area of same NUMA + * node are merged, otherwise pages from all nodes can be merged.

+ */ +# define VIR_NODE_MEMORY_SHARED_MERGE_ACROSS_NODES "shm_merge_across_nodes"

+ + int virNodeGetMemoryParameters(virConnectPtr conn, virTypedParameterPtr params, int *nparams, diff --git a/src/nodeinfo.c b/src/nodeinfo.c index 021eb05..6002789 100644 --- a/src/nodeinfo.c +++ b/src/nodeinfo.c @@ -1004,6 +1004,13 @@ nodeSetMemoryParameters(virConnectPtr conn ATTRIBUTE_UNUSED, /* Out of memory */ if (ret == -2) return -1; + } else if (STREQ(param->field, + VIR_NODE_MEMORY_SHARED_MERGE_ACROSS_NODES)) {