| Message ID | 20200424150422.17467-1-mdoucha@suse.cz |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | Add env variable as workaround for test issues in VMs | expand |
Hi Martin, > Timer tests often fail on sleep overrun when LTP is running inside a VM. > The main cause is usually that the VM doesn't get enough CPU time to wake up > the test process in time. Cannot we detect presence of "hypervisor" in flags in /proc/cpuinfo? I though it was quite reliable for detecting VM. > Disable upper bound checks in the tst_timer_test library if LTP_VM_ENV is set > to non-zero value. Kind regards, Petr
----- Original Message ----- > Hi Martin, > > > Timer tests often fail on sleep overrun when LTP is running inside a VM. > > The main cause is usually that the VM doesn't get enough CPU time to wake > > up > > the test process in time. > Cannot we detect presence of "hypervisor" in flags in /proc/cpuinfo? > I though it was quite reliable for detecting VM. We have tst_is_virt(). I see these tests fail frequently on ppc and s390, so I'm all for some switch that would make it more forgiving if running under virt.
Hi,
> We have tst_is_virt().
Thanks, Jan, nice code!
Kind regards,
Petr
On Mon, Apr 27, 2020 at 3:31 PM Jan Stancek <jstancek@redhat.com> wrote: > > > ----- Original Message ----- > > Hi Martin, > > > > > Timer tests often fail on sleep overrun when LTP is running inside a > VM. > > > The main cause is usually that the VM doesn't get enough CPU time to > wake > > > up > > > the test process in time. > > Cannot we detect presence of "hypervisor" in flags in /proc/cpuinfo? > > I though it was quite reliable for detecting VM. > > We have tst_is_virt(). > I take a rough look and doubt there is a bug in try_systemd_detect_virt(). Shouldn't strncmp() return zero the 'kvm'/'xen' is found? I guess they wanted: --- a/lib/tst_virt.c +++ b/lib/tst_virt.c @@ -93,10 +93,10 @@ static int try_systemd_detect_virt(void) if (ret) return 0; - if (strncmp("kvm", virt_type, 3)) + if (!strncmp("kvm", virt_type, 3)) return VIRT_KVM; - if (strncmp("xen", virt_type, 3)) + if (!strncmp("xen", virt_type, 3)) return VIRT_XEN; return 0; Apart from that two(kvm/xen) , we need to detect more virtualization tech for ppc/s390 I think. # uname -r 4.18.0-193.el8.s390x # systemd-detect-virt zvm
----- Original Message ----- > On Mon, Apr 27, 2020 at 3:31 PM Jan Stancek <jstancek@redhat.com> wrote: > > > > > > > ----- Original Message ----- > > > Hi Martin, > > > > > > > Timer tests often fail on sleep overrun when LTP is running inside a > > VM. > > > > The main cause is usually that the VM doesn't get enough CPU time to > > wake > > > > up > > > > the test process in time. > > > Cannot we detect presence of "hypervisor" in flags in /proc/cpuinfo? > > > I though it was quite reliable for detecting VM. > > > > We have tst_is_virt(). > > > > I take a rough look and doubt there is a bug in try_systemd_detect_virt(). > Shouldn't strncmp() return zero the 'kvm'/'xen' is found? I guess they > wanted: Yes, that looks like bug. > > --- a/lib/tst_virt.c > +++ b/lib/tst_virt.c > @@ -93,10 +93,10 @@ static int try_systemd_detect_virt(void) > if (ret) > return 0; > > - if (strncmp("kvm", virt_type, 3)) > + if (!strncmp("kvm", virt_type, 3)) > return VIRT_KVM; > > - if (strncmp("xen", virt_type, 3)) > + if (!strncmp("xen", virt_type, 3)) > return VIRT_XEN; > > return 0; > > Apart from that two(kvm/xen) , we need to detect more virtualization tech > for ppc/s390 I think. We could return VIRT_OTHER by default. We don't really need to differentiate which one it is for purpose of this patch.
Hi, > > I take a rough look and doubt there is a bug in try_systemd_detect_virt(). > > Shouldn't strncmp() return zero the 'kvm'/'xen' is found? I guess they > > wanted: > Yes, that looks like bug. Good catch! > > --- a/lib/tst_virt.c > > +++ b/lib/tst_virt.c > > @@ -93,10 +93,10 @@ static int try_systemd_detect_virt(void) > > if (ret) > > return 0; > > - if (strncmp("kvm", virt_type, 3)) > > + if (!strncmp("kvm", virt_type, 3)) > > return VIRT_KVM; > > - if (strncmp("xen", virt_type, 3)) > > + if (!strncmp("xen", virt_type, 3)) > > return VIRT_XEN; > > return 0; > > Apart from that two(kvm/xen) , we need to detect more virtualization tech > > for ppc/s390 I think. > We could return VIRT_OTHER by default. We don't really need to > differentiate which one it is for purpose of this patch. +1. And if we ever need to differentiate, we can always add them later, using code from systemd-detect-virt https://github.com/systemd/systemd/blob/master/src/basic/virt.c Kind regards, Petr
On 27. 04. 20 11:19, Petr Vorel wrote: > Hi, > >>> I take a rough look and doubt there is a bug in try_systemd_detect_virt(). >>> Shouldn't strncmp() return zero the 'kvm'/'xen' is found? I guess they >>> wanted: > >> Yes, that looks like bug. > Good catch! > >>> --- a/lib/tst_virt.c >>> +++ b/lib/tst_virt.c >>> @@ -93,10 +93,10 @@ static int try_systemd_detect_virt(void) >>> if (ret) >>> return 0; > >>> - if (strncmp("kvm", virt_type, 3)) >>> + if (!strncmp("kvm", virt_type, 3)) >>> return VIRT_KVM; > >>> - if (strncmp("xen", virt_type, 3)) >>> + if (!strncmp("xen", virt_type, 3)) >>> return VIRT_XEN; > >>> return 0; > >>> Apart from that two(kvm/xen) , we need to detect more virtualization tech >>> for ppc/s390 I think. > >> We could return VIRT_OTHER by default. We don't really need to >> differentiate which one it is for purpose of this patch. > +1. And if we ever need to differentiate, we can always add them later, using > code from systemd-detect-virt > https://github.com/systemd/systemd/blob/master/src/basic/virt.c > > Kind regards, > Petr > And while we're at it, let's also fix the buffer overflow in is_xen() and make try_systemd_detect_virt() public. I'll send a patch.
diff --git a/doc/user-guide.txt b/doc/user-guide.txt index 13865bc88..20f9c50ad 100644 --- a/doc/user-guide.txt +++ b/doc/user-guide.txt @@ -16,6 +16,7 @@ For running LTP network tests see `testcases/network/README.md`. | 'LTP_TIMEOUT_MUL' | Multiply timeout, must be number >= 1 (> 1 is useful for slow machines to avoid unexpected timeout). Variable is also used in shell tests, but ceiled to int. +| 'LTP_VM_ENV' | Set to '1' if LTP is run inside a virtual machine. | 'PATH' | It's required to addjust path: `PATH="$PATH:$LTPROOT/testcases/bin"` | 'TMPDIR' | Base directory for template directory, which is required by C tests diff --git a/include/tst_test.h b/include/tst_test.h index 5bedb4f6f..8e02003c9 100644 --- a/include/tst_test.h +++ b/include/tst_test.h @@ -301,6 +301,8 @@ unsigned int tst_timeout_remaining(void); unsigned int tst_multiply_timeout(unsigned int timeout); void tst_set_timeout(int timeout); +int tst_vm_env(void); + /* * Returns path to the test temporary directory in a newly allocated buffer. diff --git a/lib/tst_test.c b/lib/tst_test.c index 64cd3ac33..4facd4bf8 100644 --- a/lib/tst_test.c +++ b/lib/tst_test.c @@ -1378,3 +1378,14 @@ void tst_flush(void) tst_brk(TBROK | TERRNO, "fflush(stdout) failed"); } + +int tst_vm_env(void) +{ + const char *env = getenv("LTP_VM_ENV"); + + if (env) { + return atoi(env); + } + + return 0; +} diff --git a/lib/tst_timer_test.c b/lib/tst_timer_test.c index 13e9deff2..ff3a53c36 100644 --- a/lib/tst_timer_test.c +++ b/lib/tst_timer_test.c @@ -26,6 +26,7 @@ static long long *samples; static unsigned int cur_sample; static unsigned int monotonic_resolution; static unsigned int timerslack; +static int virt_env; static char *print_frequency_plot; static char *file_name; @@ -306,7 +307,7 @@ void do_timer_test(long long usec, unsigned int nsamples) samples[nsamples-1], samples[0], median, 1.00 * trunc_mean / keep_samples, discard); - if (trunc_mean > (nsamples - discard) * usec + threshold) { + if (!virt_env && trunc_mean > (nsamples - discard) * usec + threshold) { tst_res(TFAIL, "%s slept for too long", scall); if (!print_frequency_plot) @@ -343,6 +344,11 @@ static void timer_setup(void) if (setup) setup(); + /* + * Running tests in VM may cause timing issues, disable upper bound + * checks if LTP_VM_ENV is set to non-zero. + */ + virt_env = tst_vm_env(); tst_clock_getres(CLOCK_MONOTONIC, &t); tst_res(TINFO, "CLOCK_MONOTONIC resolution %lins", (long)t.tv_nsec);
Timer tests often fail on sleep overrun when LTP is running inside a VM. The main cause is usually that the VM doesn't get enough CPU time to wake up the test process in time. Disable upper bound checks in the tst_timer_test library if LTP_VM_ENV is set to non-zero value. Signed-off-by: Martin Doucha <mdoucha@suse.cz> --- doc/user-guide.txt | 1 + include/tst_test.h | 2 ++ lib/tst_test.c | 11 +++++++++++ lib/tst_timer_test.c | 8 +++++++- 4 files changed, 21 insertions(+), 1 deletion(-)