Re: [libvirt] [RFC v3 PATCH 1/5] PowerPC : Use sysfs to gather host topology, in place of /proc/cpuinfo

From: Prerna Saxena <prerna(a)linux.vnet.ibm.com&gt; Date: Mon, 3 Oct 2011 05:45:30 -0700 Subject: [PATCH 1/5] Use sysfs to gather host topology, in place of /proc/cpuinfo Libvirt at present depends on /proc/cpuinfo to gather host details such as CPUs, cores, threads, etc. This is an architecture- dependent approach. An alternative is to use 'Sysfs', which provides a platform-agnostic interface to parse host CPU topology. Signed-off-by: Prerna Saxena <prerna(a)linux.vnet.ibm.com&gt; --- src/nodeinfo.c | 114 +++++++++++++++++++------------------------------------- 1 files changed, 39 insertions(+), 75 deletions(-) diff --git a/src/nodeinfo.c b/src/nodeinfo.c index 6448b79..f70654a 100644 --- a/src/nodeinfo.c +++ b/src/nodeinfo.c @@ -30,6 +30,7 @@ #include <errno.h> #include <dirent.h> #include <sys/utsname.h> +#include <sched.h> #if HAVE_NUMACTL # define NUMA_VERSION1_COMPATIBILITY 1 @@ -67,8 +68,7 @@ /* NB, this is not static as we need to call it from the testsuite */ int linuxNodeInfoCPUPopulate(FILE *cpuinfo, - virNodeInfoPtr nodeinfo, - bool need_hyperthreads); + virNodeInfoPtr nodeinfo); static int linuxNodeGetCPUStats(FILE *procstat, int cpuNum, @@ -191,23 +191,26 @@ static int parse_socket(unsigned int cpu) return ret; } +static int parse_core(unsigned int cpu) +{ + return get_cpu_value(cpu, "topology/core_id", false); +} + int linuxNodeInfoCPUPopulate(FILE *cpuinfo, - virNodeInfoPtr nodeinfo, - bool need_hyperthreads) + virNodeInfoPtr nodeinfo) { char line[1024]; DIR *cpudir = NULL; struct dirent *cpudirent = NULL; unsigned int cpu; - unsigned long cur_threads; - int socket; - unsigned long long socket_mask = 0; - unsigned int remaining; + unsigned long core, socket, cur_threads; + cpu_set_t core_mask; + cpu_set_t socket_mask; int online; nodeinfo->cpus = 0; nodeinfo->mhz = 0; - nodeinfo->cores = 1; + nodeinfo->cores = 0; nodeinfo->nodes = 1; # if HAVE_NUMACTL @@ -221,20 +224,10 @@ int linuxNodeInfoCPUPopulate(FILE *cpuinfo, /* NOTE: hyperthreads are ignored here; they are parsed out of /sys */ while (fgets(line, sizeof(line), cpuinfo) != NULL) { char *buf = line; - if (STRPREFIX(buf, "processor")) { /* aka a single logical CPU */ - buf += 9; - while (*buf && c_isspace(*buf)) - buf++; - if (*buf != ':') { - nodeReportError(VIR_ERR_INTERNAL_ERROR, - "%s", _("parsing cpuinfo processor")); - return -1; - } - nodeinfo->cpus++; # if defined(__x86_64__) || \ defined(__amd64__) || \ defined(__i386__) - } else if (STRPREFIX(buf, "cpu MHz")) { + if (STRPREFIX(buf, "cpu MHz")) { char *p; unsigned int ui; buf += 9; @@ -249,24 +242,9 @@ int linuxNodeInfoCPUPopulate(FILE *cpuinfo, /* Accept trailing fractional part. */ && (*p == '\0' || *p == '.' || c_isspace(*p))) nodeinfo->mhz = ui; - } else if (STRPREFIX(buf, "cpu cores")) { /* aka cores */ - char *p; - unsigned int id; - buf += 9; - while (*buf && c_isspace(*buf)) - buf++; - if (*buf != ':' || !buf[1]) { - nodeReportError(VIR_ERR_INTERNAL_ERROR, - _("parsing cpuinfo cpu cores %c"), *buf); - return -1; - } - if (virStrToLong_ui(buf+1, &p, 10, &id) == 0 - && (*p == '\0' || c_isspace(*p)) - && id > nodeinfo->cores) - nodeinfo->cores = id; # elif defined(__powerpc__) || \ defined(__powerpc64__) - } else if (STRPREFIX(buf, "clock")) { + if (STRPREFIX(buf, "clock")) { char *p; unsigned int ui; buf += 5; @@ -281,53 +259,30 @@ int linuxNodeInfoCPUPopulate(FILE *cpuinfo, /* Accept trailing fractional part. */ && (*p == '\0' || *p == '.' || c_isspace(*p))) nodeinfo->mhz = ui; -# elif defined(__s390__) || \ - defined(__s390x__) - } else if (STRPREFIX(buf, "# processors")) { - char *p; - unsigned int ui; - buf += 12; - while (*buf && c_isspace(*buf)) - buf++; - if (*buf != ':' || !buf[1]) { - nodeReportError(VIR_ERR_INTERNAL_ERROR, - _("parsing number of processors %c"), *buf); - return -1; - } - if (virStrToLong_ui(buf+1, &p, 10, &ui) == 0 - && (*p == '\0' || c_isspace(*p))) - nodeinfo->cpus = ui; /* No other interesting infos are available in /proc/cpuinfo. * However, there is a line identifying processor's version, * identification and machine, but we don't want it to be caught * and parsed in next iteration, because it is not in expected * format and thus lead to error. */ - break; # else # warning Parser for /proc/cpuinfo needs to be adapted for your architecture # endif } } - if (!nodeinfo->cpus) { - nodeReportError(VIR_ERR_INTERNAL_ERROR, - "%s", _("no cpus found")); - return -1; - } - - if (!need_hyperthreads) - return 0; - - /* OK, we've parsed what we can out of /proc/cpuinfo. Get the socket - * and thread information from /sys + /* OK, we've parsed clock speed out of /proc/cpuinfo. Get the core, socket + * thread and topology information from /sys */ - remaining = nodeinfo->cpus; cpudir = opendir(CPU_SYS_PATH); if (cpudir == NULL) { virReportSystemError(errno, _("cannot opendir %s"), CPU_SYS_PATH); return -1; } - while ((errno = 0), remaining && (cpudirent = readdir(cpudir))) { + + CPU_ZERO(&core_mask); + CPU_ZERO(&socket_mask); + + while ((cpudirent = readdir(cpudir))) { if (sscanf(cpudirent->d_name, "cpu%u", &cpu) != 1) continue; @@ -338,15 +293,19 @@ int linuxNodeInfoCPUPopulate(FILE *cpuinfo, } if (!online) continue; - remaining--; + nodeinfo->cpus++; - socket = parse_socket(cpu); - if (socket < 0) { - closedir(cpudir); - return -1; + /* Parse core */ + core = parse_core(cpu); + if (!CPU_ISSET(core, &core_mask)) { + CPU_SET(core, &core_mask); + nodeinfo->cores++; } - if (!(socket_mask & (1 << socket))) { - socket_mask |= (1 << socket); + + /* Parse socket */ + socket = parse_socket(cpu); + if (!CPU_ISSET(socket, &socket_mask)) { + CPU_SET(socket, &socket_mask); nodeinfo->sockets++; } @@ -367,7 +326,12 @@ int linuxNodeInfoCPUPopulate(FILE *cpuinfo, closedir(cpudir); - /* there should always be at least one socket and one thread */ + /* there should always be at least one cpu, socket and one thread */ + if (nodeinfo->cpus == 0) { + nodeReportError(VIR_ERR_INTERNAL_ERROR, + "%s", _("no CPUs found")); + return -1; + } if (nodeinfo->sockets == 0) { nodeReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("no sockets found")); @@ -617,7 +581,7 @@ int nodeGetInfo(virConnectPtr conn ATTRIBUTE_UNUSED, virNodeInfoPtr nodeinfo) { _("cannot open %s"), CPUINFO_PATH); return -1; } - ret = linuxNodeInfoCPUPopulate(cpuinfo, nodeinfo, true); + ret = linuxNodeInfoCPUPopulate(cpuinfo, nodeinfo); VIR_FORCE_FCLOSE(cpuinfo); if (ret < 0) return -1;