On 11/13/2012 05:54 AM, Viktor Mihajlovski wrote:
Since /sys/devices/system/cpu/present is not available on older kernels like on RHEL 5.x nodeGetCPUCount will fail there. The fallback implemented is to scan for /sys/devices/system/cpu/cpuNN entries.
Signed-off-by: Viktor Mihajlovski <mihajlov@linux.vnet.ibm.com> --- src/nodeinfo.c | 33 ++++++++++++++++++++++++++++----- 1 file changed, 28 insertions(+), 5 deletions(-)
#ifdef __linux__ - /* XXX should we also work on older kernels, like RHEL5, that lack - * cpu/present and cpu/online files? Those kernels also lack cpu - * hotplugging, so it would be a matter of finding the largest - * cpu/cpuNN directory, and returning NN + 1 */ - return linuxParseCPUmax(SYSFS_SYSTEM_PATH "/cpu/present"); + /* to support older kernels, like RHEL5, that lack + * cpu/present we fall back to count cpu/cpuNN + * entries. + */ + char *cpupath = NULL; + int i = 0; + + if (virFileExists(SYSFS_SYSTEM_PATH "/cpu/present")) { + i = linuxParseCPUmax(SYSFS_SYSTEM_PATH "/cpu/present"); + } else if (virFileExists(SYSFS_SYSTEM_PATH "/cpu/cpu0")) { + do { + i++; + VIR_FREE(cpupath); + if (virAsprintf(&cpupath, "%s/cpu/cpu%d", + SYSFS_SYSTEM_PATH, i) < 0) { + virReportOOMError(); + return -1; + } + } while (virFileExists(cpupath));
The assumption here is that any kernel lacking cpu/present also lacks hotplug, and therefore the cpuNN will be consecutive and we aren't going to miss anything. You removed that assumption from the comment, but I think it is important to leave in. ACK. I'm firing up my RHEL 5 VM to test this before I push with this comment change, but it looks sane. diff --git i/src/nodeinfo.c w/src/nodeinfo.c index cea3775..4589b77 100644 --- i/src/nodeinfo.c +++ w/src/nodeinfo.c @@ -978,9 +978,10 @@ int nodeGetCPUCount(void) { #ifdef __linux__ - /* to support older kernels, like RHEL5, that lack - * cpu/present we fall back to count cpu/cpuNN - * entries. + /* To support older kernels that lack cpu/present, such as 2.6.18 + * in RHEL5, we fall back to count cpu/cpuNN entries; this assumes + * that such kernels also lack hotplug, and therefore cpu/cpuNN + * will be consecutive. */ char *cpupath = NULL; int i = 0; -- Eric Blake eblake@redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org