Re: [PATCH v1 09/10] capabilities: Expose NUMA interconnects

Links between NUMA nodes can have different latencies and bandwidths. This info is newly defined in ACPI 6.2 under Heterogeneous Memory Attribute Table (HMAT) table. Linux kernel learned how to report these values under sysfs and thus we can expose them in our capabilities XML. The sysfs interface is documented in kernel's Documentation/admin-guide/mm/numaperf.rst. Long story short, two nodes can be in initiator-target relationship. A node can be initiator if it has a CPU or a device that's capable of initiating memory transfer. Therefore a node that has just memory can only be target. An initiator-target link can then have any combination of {bandwidth, latency} - {access, read, write} attribute (6 in total). However, the standard says access is applicable iff read and write values are the same. Therefore, we really have just four combinations of attributes: bandwidth-read, bandwidth-write, latency-read, latency-write. This is the combination that kernel reports anyway. Then, under /sys/system/devices/node/nodeX/acccess0/initiators we find values for those 4 attributes and also symlinks named "nodeN" which then represent initiators to nodeX. For instance: /sys/system/node/node1/access0/initiators/node0 -> ../../node0 /sys/system/node/node1/access0/initiators/read_bandwidth /sys/system/node/node1/access0/initiators/read_latency /sys/system/node/node1/access0/initiators/write_bandwidth /sys/system/node/node1/access0/initiators/write_latency This means that node0 is initiator and node1 is target and values of the interconnect can be read. In theory, there can be separate links to memory side caches too (e.g. one link from node X to node Y's main memory, another from node X to node Y's L1 cache, another one to L2 cache and so on). But sysfs does not express this relationship just yet. Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1786309 Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; --- docs/schemas/capability.rng | 3 + src/conf/capabilities.c | 181 +++++++++++++++++++++++++++++++++++- src/conf/capabilities.h | 1 + 3 files changed, 184 insertions(+), 1 deletion(-) diff --git a/src/conf/capabilities.c b/src/conf/capabilities.c index 7b60676070..8f2d7b75d7 100644 --- a/src/conf/capabilities.c +++ b/src/conf/capabilities.c @@ -1735,6 +1743,174 @@ virCapabilitiesHostNUMAInitFake(virCapsHostNUMA *caps) } +static void +virCapabilitiesHostInsertHMAT(GArray *interconnects, + int initiator, + int target, + unsigned int read_bandwidth, + unsigned int write_bandwidth, + unsigned int read_latency, + unsigned int write_latency) +{ + virNumaInterconnect ni; + + ni = (virNumaInterconnect) { VIR_NUMA_INTERCONNECT_TYPE_BANDWIDTH, + initiator, target, 0, VIR_MEMORY_LATENCY_READ, read_bandwidth}; + g_array_append_val(interconnects, ni); + + ni = (virNumaInterconnect) { VIR_NUMA_INTERCONNECT_TYPE_BANDWIDTH, + initiator, target, 0, VIR_MEMORY_LATENCY_WRITE, write_bandwidth}; + g_array_append_val(interconnects, ni); + + ni = (virNumaInterconnect) { VIR_NUMA_INTERCONNECT_TYPE_LATENCY, + initiator, target, 0, VIR_MEMORY_LATENCY_READ, read_latency}; + g_array_append_val(interconnects, ni); + + ni = (virNumaInterconnect) { VIR_NUMA_INTERCONNECT_TYPE_LATENCY, + initiator, target, 0, VIR_MEMORY_LATENCY_WRITE, write_latency}; + g_array_append_val(interconnects, ni); +} + + +static int +virCapabilitiesHostNUMAInitInterconnectsNode(GArray *interconnects, + int node) +{ + g_autofree char *path = NULL; + g_autofree char *initPath = NULL; + g_autoptr(DIR) dir = NULL; + int direrr = 0; + struct dirent *entry; + unsigned int read_bandwidth; + unsigned int write_bandwidth; + unsigned int read_latency; + unsigned int write_latency; + + path = g_strdup_printf(SYSFS_SYSTEM_PATH "/node/node%d/access0", node); +

+ if (!virFileExists(path)) + return 0; + + if (virCapabilitiesGetNodeCacheReadFile(path, "initiators", + "read_bandwidth", + &read_bandwidth) < 0) + return -1; + if (virCapabilitiesGetNodeCacheReadFile(path, "initiators", + "write_bandwidth", + &write_bandwidth) < 0) + return -1; + + /* Bandwidths are read in MiB but stored in KiB */ + read_bandwidth <<= 10; + write_bandwidth <<= 10; + + if (virCapabilitiesGetNodeCacheReadFile(path, "initiators", + "read_latency", + &read_latency) < 0) + return -1; + if (virCapabilitiesGetNodeCacheReadFile(path, "initiators", + "write_latency", + &write_latency) < 0) + return -1; + + initPath = g_strdup_printf("%s/initiators", path); + + if (virDirOpen(&dir, initPath) < 0) + return -1; + + while ((direrr = virDirRead(dir, &entry, path)) > 0) { + const char *dname = STRSKIP(entry->d_name, "node"); + int initNode; + + if (!dname) + continue; + + if (virStrToLong_i(dname, NULL, 10, &initNode) < 0) {

+ virReportError(VIR_ERR_INTERNAL_ERROR, + _("unable to parse %s"), + entry->d_name); + return -1; + } + + virCapabilitiesHostInsertHMAT(interconnects, + initNode, node, + read_bandwidth, + write_bandwidth, + read_latency, + write_latency); + } + + return 0; +} + + +static int +virCapsHostNUMAInterconnectComparator(const void *a, + const void *b) +{ + const virNumaInterconnect *aa = a; + const virNumaInterconnect *bb = b; + + if (aa->type != bb->type) + return aa->type - bb->type; + + if (aa->initiator != bb->initiator) + return aa->initiator - bb->initiator; + + if (aa->target != bb->target) + return aa->target - bb->target; + + if (aa->cache != bb->cache) + return aa->cache - bb->cache; + + if (aa->accessType != bb->accessType) + return aa->accessType - bb->accessType; + + return aa->value - bb->value; +} + + +static int +virCapabilitiesHostNUMAInitInterconnects(virCapsHostNUMA *caps) +{ + g_autoptr(DIR) dir = NULL; + int direrr = 0; + struct dirent *entry; + g_autofree char *path = NULL; + g_autoptr(GArray) interconnects = g_array_new(FALSE, FALSE, sizeof(virNumaInterconnect)); + + path = g_strdup_printf(SYSFS_SYSTEM_PATH "/node/");

+ + if (virDirOpenIfExists(&dir, path) < 0) + return -1; + + while (dir && (direrr = virDirRead(dir, &entry, path)) > 0) { + const char *dname = STRSKIP(entry->d_name, "node"); + int node; + + if (!dname) + continue; + + if (virStrToLong_i(dname, NULL, 10, &node) < 0) {