pkg/sysinfo/checkCgroupPids: speedup

For some reason this code chose not to use information already fetched,
and call cgroups.FindCgroupMountpoint() instead. This is not a cheap
call, as it has to parse the whole nine yards of /proc/self/mountinfo,
and the info it tries to get (whether the pids controller is present)
is already available from cgMounts map.

Signed-off-by: Kir Kolyshkin <[email protected]>

pkg/sysinfo/sysinfo_linux.go

@@ -40,7 +40,7 @@ func New(quiet bool) *SysInfo {
 		sysInfo.cgroupCPUInfo = checkCgroupCPU(cgMounts, quiet)
 		sysInfo.cgroupBlkioInfo = checkCgroupBlkioInfo(cgMounts, quiet)
 		sysInfo.cgroupCpusetInfo = checkCgroupCpusetInfo(cgMounts, quiet)
-		sysInfo.cgroupPids = checkCgroupPids(quiet)
+		sysInfo.cgroupPids = checkCgroupPids(cgMounts, quiet)
 	}
 
 	_, ok := cgMounts["devices"]
@@ -227,17 +227,17 @@ func checkCgroupCpusetInfo(cgMounts map[string]string, quiet bool) cgroupCpusetI
 }
 
 // checkCgroupPids reads the pids information from the pids cgroup mount point.
-func checkCgroupPids(quiet bool) cgroupPids {
+func checkCgroupPids(cgMounts map[string]string, quiet bool) cgroupPids {
 	cgroup2, err := cgroupv2.Enabled()
 	if err != nil {
 		logrus.Errorf("Failed to check cgroups version: %v", err)
 		return cgroupPids{}
 	}
 	if !cgroup2 {
-		_, err := cgroups.FindCgroupMountpoint("", "pids")
-		if err != nil {
+		_, ok := cgMounts["pids"]
+		if !ok {
 			if !quiet {
-				logrus.Warn(err)
+				logrus.Warn("unable to find pids cgroup in mounts")
 			}
 			return cgroupPids{}
 		}