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cgroup: improve isolcpus handling

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- add more logging
- only write to cpuset.cpus if we really have to
- simplify cleanup on error and success

Signed-off-by: Christian Brauner <christian.brauner@canonical.com>
This commit is contained in:
Christian Brauner
2016-11-21 18:11:32 +01:00
parent b8ca2bc7c9
commit 6f9584d885
1 changed files with 66 additions and 24 deletions
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90
src/lxc/cgroups/cgfsng.c
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@@ -420,6 +420,7 @@ static ssize_t get_max_cpus(char *cpulist)
return cpus;
}
#define __ISOL_CPUS "/sys/devices/system/cpu/isolated"
static bool filter_and_set_cpus(char *path, bool am_initialized)
{
char *lastslash, *fpath, oldv;
@@ -429,78 +430,108 @@ static bool filter_and_set_cpus(char *path, bool am_initialized)
ssize_t maxposs = 0, maxisol = 0;
char *cpulist = NULL, *posscpus = NULL, *isolcpus = NULL;
uint32_t *possmask = NULL, *isolmask = NULL;
bool bret = false;
bool bret = false, flipped_bit = false;
lastslash = strrchr(path, '/');
if (!lastslash) { // bug... this shouldn't be possible
ERROR("cgfsng:copy_parent_file: bad path %s", path);
ERROR("Invalid path: %s.", path);
return bret;
}
oldv = *lastslash;
*lastslash = '\0';
fpath = must_make_path(path, "cpuset.cpus", NULL);
posscpus = read_file(fpath);
if (!posscpus)
goto cleanup;
if (!posscpus) {
SYSERROR("Could not read file: %s.\n", fpath);
goto on_error;
}
/* Get maximum number of cpus found in possible cpuset. */
maxposs = get_max_cpus(posscpus);
if (maxposs < 0)
goto cleanup;
goto on_error;
isolcpus = read_file("/sys/devices/system/cpu/isolated");
if (!isolcpus)
goto cleanup;
if (!file_exists(__ISOL_CPUS)) {
/* This system doesn't expose isolated cpus. */
DEBUG("Path: "__ISOL_CPUS" to read isolated cpus from does not exist.\n");
goto on_success;
}
isolcpus = read_file(__ISOL_CPUS);
if (!isolcpus) {
SYSERROR("Could not read file "__ISOL_CPUS);
goto on_error;
}
if (!isdigit(isolcpus[0])) {
DEBUG("No isolated cpus detected.");
cpulist = posscpus;
/* No isolated cpus but we weren't already initialized by
* someone. We should simply copy the parents cpuset.cpus
* values.
*/
if (!am_initialized)
if (!am_initialized) {
DEBUG("Copying cpuset of parent cgroup.");
goto copy_parent;
}
/* No isolated cpus but we were already initialized by someone.
* Nothing more to do for us.
*/
bret = true;
goto cleanup;
goto on_success;
}
/* Get maximum number of cpus found in isolated cpuset. */
maxisol = get_max_cpus(isolcpus);
if (maxisol < 0)
goto cleanup;
goto on_error;
if (maxposs < maxisol)
maxposs = maxisol;
maxposs++;
possmask = lxc_cpumask(posscpus, maxposs);
if (!possmask)
goto cleanup;
if (!possmask) {
ERROR("Could not create cpumask for all possible cpus.\n");
goto on_error;
}
isolmask = lxc_cpumask(isolcpus, maxposs);
if (!isolmask)
goto cleanup;
if (!isolmask) {
ERROR("Could not create cpumask for all isolated cpus.\n");
goto on_error;
}
for (i = 0; i <= maxposs; i++) {
if (is_set(i, isolmask) && is_set(i, possmask)) {
flipped_bit = true;
clear_bit(i, possmask);
}
}
if (!flipped_bit) {
DEBUG("No isolated cpus present in cpuset.");
goto on_success;
}
DEBUG("Removed isolated cpus from cpuset.");
cpulist = lxc_cpumask_to_cpulist(possmask, maxposs);
if (!cpulist) /* Bug */
goto cleanup;
if (!cpulist) {
ERROR("Could not create cpu list.\n");
goto on_error;
}
copy_parent:
*lastslash = oldv;
fpath = must_make_path(path, "cpuset.cpus", NULL);
ret = lxc_write_to_file(fpath, cpulist, strlen(cpulist), false);
if (!ret)
bret = true;
if (ret < 0) {
SYSERROR("Could not write cpu list to: %s.\n", fpath);
goto on_error;
}
cleanup:
on_success:
bret = true;
on_error:
free(fpath);
free(isolcpus);
@@ -579,6 +610,7 @@ static bool handle_cpuset_hierarchy(struct hierarchy *h, char *cgname)
free(cgpath);
return false;
}
clonechildrenpath = must_make_path(cgpath, "cgroup.clone_children", NULL);
if (!file_exists(clonechildrenpath)) { /* unified hierarchy doesn't have clone_children */
free(clonechildrenpath);
@@ -593,10 +625,15 @@ static bool handle_cpuset_hierarchy(struct hierarchy *h, char *cgname)
}
/* Make sure any isolated cpus are removed from cpuset.cpus. */
if (!filter_and_set_cpus(cgpath, v == '1'))
if (!filter_and_set_cpus(cgpath, v == '1')) {
SYSERROR("Failed to remove isolated cpus.");
free(clonechildrenpath);
free(cgpath);
return false;
}
if (v == '1') { /* already set for us by someone else */
DEBUG("\"cgroup.clone_children\" was already set to \"1\".");
free(clonechildrenpath);
free(cgpath);
return true;
@@ -604,6 +641,7 @@ static bool handle_cpuset_hierarchy(struct hierarchy *h, char *cgname)
/* copy parent's settings */
if (!copy_parent_file(cgpath, "cpuset.mems")) {
SYSERROR("Failed to copy \"cpuset.mems\" settings.");
free(cgpath);
free(clonechildrenpath);
return false;
@@ -1256,10 +1294,14 @@ struct cgroup_ops *cgfsng_ops_init(void)
static bool create_path_for_hierarchy(struct hierarchy *h, char *cgname)
{
h->fullcgpath = must_make_path(h->mountpoint, h->base_cgroup, cgname, NULL);
if (dir_exists(h->fullcgpath)) // it must not already exist
if (dir_exists(h->fullcgpath)) { // it must not already exist
ERROR("Path \"%s\" already existed.", h->fullcgpath);
return false;
if (!handle_cpuset_hierarchy(h, cgname))
}
if (!handle_cpuset_hierarchy(h, cgname)) {
ERROR("Failed to handle cgroupfs v1 cpuset controller.");
return false;
}
return mkdir_p(h->fullcgpath, 0755) == 0;
}