This commit tries to fix a 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 automatic 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@xxxxxxxxx>
---
src/lxc/lxc_cgroup.c | 31 ++++++++++++++++
src/lxc/lxc_container.c | 15 ++++++++
src/lxc/lxc_fuse.c | 78 ++++++++++++++++++++++++++++++++++++++---
3 files changed, 120 insertions(+), 4 deletions(-)
diff --git a/src/lxc/lxc_cgroup.c b/src/lxc/lxc_cgroup.c
index 470337e675..a6c73d9d55 100644
--- a/src/lxc/lxc_cgroup.c
+++ b/src/lxc/lxc_cgroup.c
@@ -59,6 +59,34 @@ 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 virLXCCgroupSetupCpusetTune(virDomainDefPtr def,
virCgroupPtr cgroup,
virBitmapPtr nodemask)
@@ -76,6 +104,9 @@ static int virLXCCgroupSetupCpusetTune(virDomainDefPtr def,
goto cleanup;
/* free mask to make sure we won't use it in a wrong way later */
VIR_FREE(mask);
+ } else {
+ /* auto mode for VCPU limits */
+ virLXCCgroupSetupVcpuAuto(def, cgroup);
}
if (virDomainNumatuneGetMode(def->numa, -1, &mode) < 0 ||
diff --git a/src/lxc/lxc_container.c b/src/lxc/lxc_container.c
index 41efe43a14..1a2c97c9f4 100644
--- a/src/lxc/lxc_container.c
+++ b/src/lxc/lxc_container.c
@@ -999,6 +999,7 @@ static int lxcContainerMountProcFuse(virDomainDefPtr def,
{
int ret;
char *meminfo_path = NULL;
+ char *cpuinfo_path = NULL;
VIR_DEBUG("Mount /proc/meminfo stateDir=%s", stateDir);
@@ -1013,7 +1014,21 @@ static int lxcContainerMountProcFuse(virDomainDefPtr def,
meminfo_path);
}
+ VIR_DEBUG("Mount /proc/cpuinfo stateDir=%s", stateDir);
+
+ cpuinfo_path = g_strdup_printf("/.oldroot/%s/%s.fuse/cpuinfo",
+ stateDir,
+ def->name);
+
+ if ((ret = mount(cpuinfo_path, "/proc/cpuinfo",
+ NULL, MS_BIND, NULL)) < 0) {
+ virReportSystemError(errno,
+ _("Failed to mount %s on /proc/cpuinfo"),
+ cpuinfo_path);
+ }
+
VIR_FREE(meminfo_path);
+ VIR_FREE(cpuinfo_path);
return ret;
}
#else
diff --git a/src/lxc/lxc_fuse.c b/src/lxc/lxc_fuse.c
index 44f240a0b5..12fa69d494 100644
--- a/src/lxc/lxc_fuse.c
+++ b/src/lxc/lxc_fuse.c
@@ -37,6 +37,7 @@
#if WITH_FUSE
static const char *fuse_meminfo_path = "/meminfo";
+static const char *fuse_cpuinfo_path = "/cpuinfo";
static int lxcProcGetattr(const char *path, struct stat *stbuf)
{
@@ -54,7 +55,8 @@ static int lxcProcGetattr(const char *path, struct stat *stbuf)
if (STREQ(path, "/")) {
stbuf->st_mode = S_IFDIR | 0755;
stbuf->st_nlink = 2;
- } else if (STREQ(path, fuse_meminfo_path)) {
+ } else if (STREQ(path, fuse_meminfo_path) ||
+ STREQ(path, fuse_cpuinfo_path)) {
if (stat(mempath, &sb) < 0) {
res = -errno;
goto cleanup;
@@ -90,6 +92,7 @@ static int lxcProcReaddir(const char *path, void *buf,
filler(buf, ".", NULL, 0);
filler(buf, "..", NULL, 0);
filler(buf, fuse_meminfo_path + 1, NULL, 0);
+ filler(buf, fuse_cpuinfo_path + 1, NULL, 0);
return 0;
}
@@ -97,7 +100,8 @@ static int lxcProcReaddir(const char *path, void *buf,
static int lxcProcOpen(const char *path G_GNUC_UNUSED,
struct fuse_file_info *fi G_GNUC_UNUSED)
{
- if (STRNEQ(path, fuse_meminfo_path))
+ if (STRNEQ(path, fuse_meminfo_path) &&
+ STRNEQ(path, fuse_cpuinfo_path))
return -ENOENT;
if ((fi->flags & 3) != O_RDONLY)
@@ -125,7 +129,7 @@ static int lxcProcHostRead(char *path, char *buf, size_t size, off_t offset)
static int lxcProcReadMeminfo(char *hostpath, virDomainDefPtr def,
char *buf, size_t size, off_t offset)
{
- int res;
+ int res = -1;
FILE *fd = NULL;
char *line = NULL;
size_t n;
@@ -151,7 +155,6 @@ static int lxcProcReadMeminfo(char *hostpath, virDomainDefPtr def,
goto cleanup;
}
- res = -1;
while (getline(&line, &n, fd) > 0) {
char *ptr = strchr(line, ':');
if (!ptr)
@@ -235,6 +238,70 @@ static int lxcProcReadMeminfo(char *hostpath, virDomainDefPtr def,
return res;
}
+
+static int lxcProcReadCpuinfo(char *hostpath, virDomainDefPtr def,
+ char *buf, size_t size, off_t offset)
+{
+ int res = -1;
+ FILE *fd = NULL;
+ char *line = NULL;
+ size_t n;
+ virBuffer buffer = VIR_BUFFER_INITIALIZER;
+ virBufferPtr new_cpuinfo = &buffer;
+ size_t cpu;
+ size_t nvcpu;
+ size_t curcpu = 0;
+ bool get_proc = false;
+
+ fd = fopen(hostpath, "r");
+ if (fd == NULL) {
+ virReportSystemError(errno, _("Cannot open %s"), hostpath);
+ res = -errno;
+ goto cleanup;
+ }
+
+ /* /proc/cpuinfo does not support fseek */
+ if (offset > 0) {
+ res = 0;
+ goto cleanup;
+ }
+
+ nvcpu = virDomainDefGetVcpus(def);
+ while (getline(&line, &n, fd) > 0) {
+ if (sscanf(line, "processor\t: %zu", &cpu) == 1) {
+ virDomainVcpuDefPtr vcpu = virDomainDefGetVcpu(def, cpu);
+ /* VCPU is mapped */
+ if (vcpu) {
+ if (curcpu == nvcpu)
+ break;
+
+ 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)
+ virBufferAdd(new_cpuinfo, line, -1);
+ }
+ }
+
+ res = strlen(virBufferCurrentContent(new_cpuinfo));
+ if (res > size)
+ res = size;
+ memcpy(buf, virBufferCurrentContent(new_cpuinfo), res);
+
+ cleanup:
+ VIR_FREE(line);
+ virBufferFreeAndReset(new_cpuinfo);
+ VIR_FORCE_FCLOSE(fd);
+ return res;
+}
+
+
static int lxcProcRead(const char *path G_GNUC_UNUSED,
char *buf G_GNUC_UNUSED,
size_t size G_GNUC_UNUSED,
@@ -254,6 +321,9 @@ static int lxcProcRead(const char *path G_GNUC_UNUSED,
if (STREQ(path, fuse_meminfo_path)) {
if ((res = lxcProcReadMeminfo(hostpath, def, buf, size, offset)) < 0)
res = lxcProcHostRead(hostpath, buf, size, offset);
+ } else if (STREQ(path, fuse_cpuinfo_path)) {
+ if ((res = lxcProcReadCpuinfo(hostpath, def, buf, size, offset)) < 0)
+ res = lxcProcHostRead(hostpath, buf, size, offset);
}
VIR_FREE(hostpath);
--
2.20.1
