Re: [PATCH v4 4/5] lxc: Implement virtual /proc/cpuinfo via LXC fuse

This commit tries to fix lots of issues related to LXC VCPUs. One of them is related to /proc/cpuinfo content. If only 1 VCPU is set, LXC containers will show all CPUs available for host. The second one is related to CPU share, if an user set only 1 VCPU, the container/process will use all available CPUs. (This is not the case when `cpuset` attribute is declared). So, this commit adds a virtual cpuinfo based on VCPU mapping and it automatically limits the CPU usage according VCPU count. Example (now): LXC container - 8 CPUS with 2 VCPU: lxc-root# stress --cpu 8 On host machine, only CPU 0 and 1 have 100% usage. Signed-off-by: Julio Faracco <jcfaracco(a)gmail.com&gt; --- src/lxc/lxc_cgroup.c | 31 ++++++++++++++ src/lxc/lxc_container.c | 39 ++++++++++------- src/lxc/lxc_fuse.c | 95 ++++++++++++++++++++++++++++++++++++++--- 3 files changed, 145 insertions(+), 20 deletions(-) diff --git a/src/lxc/lxc_cgroup.c b/src/lxc/lxc_cgroup.c index d29b65092a..912a252473 100644 --- a/src/lxc/lxc_cgroup.c +++ b/src/lxc/lxc_cgroup.c @@ -50,6 +50,34 @@ static int virLXCCgroupSetupCpuTune(virDomainDefPtr def, } +static int virLXCCgroupSetupVcpuAuto(virDomainDefPtr def, + virCgroupPtr cgroup) +{ + size_t i; + int vcpumax; + virBuffer buffer = VIR_BUFFER_INITIALIZER; + virBufferPtr cpuset = &buffer; + + vcpumax = virDomainDefGetVcpusMax(def); + for (i = 0; i < vcpumax; i++) { + virDomainVcpuDefPtr vcpu = virDomainDefGetVcpu(def, i); + /* Cgroup is smart enough to convert numbers separated + * by comma into ranges. Example: "0,1,2,5," -> "0-2,5". + * Libvirt does not need to process it here. */ + if (vcpu) + virBufferAsprintf(cpuset, "%zu,", i); + }

+ if (virCgroupSetCpusetCpus(cgroup, + virBufferCurrentContent(cpuset)) < 0) { + virBufferFreeAndReset(cpuset); + return -1; + } + + virBufferFreeAndReset(cpuset); + return 0; +}

+static int +lxcProcReadCpuinfoParse(virDomainDefPtr def, char *base, + virBufferPtr new_cpuinfo) +{ + char *procline = NULL; + char *saveptr = base; + size_t cpu; + size_t nvcpu; + size_t curcpu = 0; + bool get_proc = false; + + nvcpu = virDomainDefGetVcpus(def); + while ((procline = strtok_r(NULL, "\n", &saveptr))) { + if (sscanf(procline, "processor\t: %zu", &cpu) == 1) {

+ virDomainVcpuDefPtr vcpu = virDomainDefGetVcpu(def, cpu); + /* VCPU is mapped */ + if (vcpu) { + if (curcpu == nvcpu) + break; + + if (curcpu > 0) + virBufferAddLit(new_cpuinfo, "\n"); + + virBufferAsprintf(new_cpuinfo, "processor\t: %zu\n", + curcpu); + curcpu++; + get_proc = true; + } else { + get_proc = false; + } + } else { + /* It is not a processor index */ + if (get_proc) + virBufferAsprintf(new_cpuinfo, "%s\n", procline); + } + } + + virBufferAddLit(new_cpuinfo, "\n"); + + return strlen(virBufferCurrentContent(new_cpuinfo)); +}