On 7/20/21 4:55 AM, Yang Fei wrote:
On 2021/7/19 17:05, Peter Krempa wrote:
On Fri, Jul 16, 2021 at 18:42:22 +0800, Yang Fei wrote:
Add helper function virGetCpuHaltPollTime to obtain halt polling time. If the kernel support halt polling time statistic, and mount debugfs. This function will take effect on KVM VMs.
Signed-off-by: Yang Fei <yangfei85@huawei.com> --- src/libvirt_private.syms | 1 + src/util/virutil.c | 43 ++++++++++++++++++++++++++++++++++++++++ src/util/virutil.h | 4 ++++ 3 files changed, 48 insertions(+)
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms index 68e4b6aab8..64aff4eca4 100644 --- a/src/libvirt_private.syms +++ b/src/libvirt_private.syms @@ -3479,6 +3479,7 @@ virDoesUserExist; virDoubleToStr; virFormatIntDecimal; virFormatIntPretty; +virGetCpuHaltPollTime; virGetDeviceID; virGetDeviceUnprivSGIO; virGetGroupID; diff --git a/src/util/virutil.c b/src/util/virutil.c index 311cbbf93a..f5304644c0 100644 --- a/src/util/virutil.c +++ b/src/util/virutil.c @@ -1936,3 +1936,46 @@ virPipeNonBlock(int fds[2]) { return virPipeImpl(fds, true, true); } + +int +virGetCpuHaltPollTime(pid_t pid, + unsigned long long *haltPollSuccess, + unsigned long long *haltPollFail) +{ + g_autofree char *pidToStr = NULL; + g_autofree char *debugFsPath = NULL; + g_autofree char *completePath = NULL; + struct dirent *ent = NULL; + g_autoptr(DIR) dir = NULL; + int ret = -1; + bool found = false; + + if (!(debugFsPath = virFileFindMountPoint("debugfs"))) + return ret;
Here '-1' is returned, but no libvirt error is reported ...
+ + completePath = g_strdup_printf("%s/%s", debugFsPath, "kvm"); + if (virDirOpenIfExists(&dir, completePath) != 1) + return ret;
While here -1 is reported and an error may be reported (e.g on EACCESS). We generally avoid this pattern because the caller cant properly handle that.
+ + pidToStr = g_strdup_printf("%d%c", pid, '-');
I'm fairly certain this will fail to compile on mingw since %d isn't the proper formatting modifier for pid_t.
In the last version, I try to use %lld but failed in the ninja test. How about forcibly converts the variable pid to long long? Like this: g_strdup_printf("%lld%c", (long long)pid, '-') I find that this is used elsewhere in the code.
Yes, that works.
+ while (virDirRead(dir, &ent, NULL) > 0) { + if (STRPREFIX(ent->d_name, pidToStr)) {
Any idea what the suffix after '-' in the debugfs entry is? If we can figure it out we won't have to look up the correct file.
The full directory name format is "pid-fd", The fd is assigned during VM creation. As I know, we can find it in /proc/(qemu-kvm pid)/fd, but also need to look up which one points to "anon_inode:kvm-vm". That may not be any more efficient than look up it in the kvm directory.
Right. I tried to find that in the kernel sources, but wasn't successful. In that case I think you can do what you're doing. Michal