[Bug 1839852] Re: perf broken on hwe kernel 5.0.0-23
** Changed in: linux-hwe (Ubuntu) Status: Confirmed => Fix Released -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1839852 Title: perf broken on hwe kernel 5.0.0-23 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-hwe/+bug/1839852/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1839852] Re: perf broken on hwe kernel 5.0.0-23
The problem is fixed with perf in linux-hwe-tools-5.0.0-25 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1839852 Title: perf broken on hwe kernel 5.0.0-23 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-hwe/+bug/1839852/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1839852] Re: perf broken on hwe kernel 5.0.0-23
Status changed to 'Confirmed' because the bug affects multiple users. ** Changed in: linux-hwe (Ubuntu) Status: New => Confirmed -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1839852 Title: perf broken on hwe kernel 5.0.0-23 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-hwe/+bug/1839852/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1839852] Re: perf broken on hwe kernel 5.0.0-23
After some investigation, I found this:
If I use the perf executable from the package linux-tools-4.15.0-55-generic
along with the Linux kernel 5.0.0-23-generic from the package
linux-image-5.0.0-23-generic , it works.
$ /usr/lib/linux-tools/4.15.0-55-generic/perf top -p `pidof top`
Samples: 134 of event 'cycles:ppp', Event count (approx.): 26218815
Overhead Shared Object Symbol
6.69% libc-2.27.so[.] _IO_vfscanf
4.01% [kernel][k] entry_SYSCALL_64
3.71% [kernel][k] do_syscall_64
3.36% [kernel][k] num_to_str
3.25% libc-2.27.so[.] __GI_strtoll_l_internal
2.54% [kernel][k] syscall_return_via_sysret
2.35% [kernel][k] __d_lookup
2.24% [kernel][k] get_mem_cgroup_from_mm
2.22% libc-2.27.so[.] _IO_default_xsputn
1.84% libc-2.27.so[.] _IO_sputbackc
1.80% [kernel][k] kmem_cache_free
1.77% [kernel][k] bitmap_string.isra.2
1.72% [kernel][k] render_sigset_t
1.65% [kernel][k] __alloc_file
1.62% [kernel][k] do_task_stat
1.57% [kernel][k] number
So, the problem is really the executable /usr/lib/linux-hwe-tools-5.0.0-23/perf
which is in the package:
$ apt-file search /usr/lib/linux-hwe-tools-5.0.0-23/perf
linux-hwe-tools-5.0.0-23: /usr/lib/linux-hwe-tools-5.0.0-23/perf
$ dpkg -l|grep linux-hwe-tools-5.0.0-23|awk '{print $1, $2, $3, $4}'|column -t
ii linux-hwe-tools-5.0.0-23 5.0.0-23.24~18.04.1 amd64
According to
https://packages.ubuntu.com/bionic-updates/linux-hwe-cloud-tools-5.0.0-23 ,
the source package for linux-hwe-tools is linux-hwe.
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Title:
perf broken on hwe kernel 5.0.0-23
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[Bug 1839852] Re: perf broken on hwe kernel 5.0.0-23
With Linux and perf 5.0.0-23-generic (HWE or Hardware Enablement), it is
broken.
Versions
$ uname -r
5.0.0-23-generic
$ perf --version
perf version 5.0.15
$ dpkg -l|grep 5.0.0-23|awk '{print $1,$2,$3,$4}'|column -t
ii linux-headers-5.0.0-235.0.0-23.24~18.04.1 all
ii linux-headers-5.0.0-23-generic5.0.0-23.24~18.04.1 amd64
ii linux-hwe-tools-5.0.0-23 5.0.0-23.24~18.04.1 amd64
ii linux-image-5.0.0-23-generic 5.0.0-23.24~18.04.1 amd64
ii linux-modules-5.0.0-23-generic5.0.0-23.24~18.04.1 amd64
ii linux-modules-extra-5.0.0-23-generic 5.0.0-23.24~18.04.1 amd64
ii linux-tools-5.0.0-23-generic 5.0.0-23.24~18.04.1 amd64
A minimal series of steps necessary to make it happen
-
1. In a terminal tab., run:
$ top
2. In another tab, run
$ perf top -p `pidof top`
3. Look at the output of "perf top".
What you expected to happen
---
I expect to see "cycles" events being reported for the process "top"
(started at step 1.)
See section "What actually happened" in comment #1 above.
What actually happened
--
The output of "perf top -p `pidof top`" (step 2) is:
Samples: 0 of event 'cycles:ppp', 4000 Hz, Event count (approx.): 0 lost: 0/0
drop: 0/0
Overhead
It is as if there are no events being sampled.
System calls
perf_event_open System calls:
$ strace perf top -p `pidof top` 2>&1 | grep ^perf_event_open
perf_event_open({type=PERF_TYPE_HARDWARE, size=PERF_ATTR_SIZE_VER5,
config=PERF_COUNT_HW_CPU_CYCLES, ...}, 0, -1, -1, 0) = 3
perf_event_open({type=PERF_TYPE_SOFTWARE, size=0 /* PERF_ATTR_SIZE_??? */,
config=PERF_COUNT_SW_CPU_CLOCK, ...}, -1, 2, -1, PERF_FLAG_FD_CLOEXEC) = 3
perf_event_open({type=PERF_TYPE_HARDWARE, size=PERF_ATTR_SIZE_VER5,
config=PERF_COUNT_HW_CPU_CYCLES, ...}, -1, 0, -1, PERF_FLAG_FD_CLOEXEC) = 3
perf_event_open({type=PERF_TYPE_HARDWARE, size=PERF_ATTR_SIZE_VER5,
config=PERF_COUNT_HW_CPU_CYCLES, ...}, -1, 0, -1, PERF_FLAG_FD_CLOEXEC) = 3
perf_event_open({type=PERF_TYPE_HARDWARE, size=PERF_ATTR_SIZE_VER5,
config=PERF_COUNT_HW_CPU_CYCLES, ...}, 4035, -1, -1, PERF_FLAG_FD_CLOEXEC) = 3
Additional note
---
Using the full path to perf 5.0.0-23 also produce 0 events.
$ /usr/lib/linux-tools/5.0.0-23-generic/perf top -p `pidof top`
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Title:
perf broken on hwe kernel 5.0.0-23
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[Bug 1839852] Re: perf broken on hwe kernel 5.0.0-23
With Linux and perf 4.15.0-55-generic (non-HWE), it works as reported in
Ubuntu 18.04.3 LTS:
Versions
$ uname -r
4.15.0-55-generic
$ perf --version
perf version 4.15.18
In dpkg:
ii linux-image-4.15.0-55-generic 4.15.0-55.60
amd64Signed kernel image generic
ii linux-tools-common 4.15.0-55.60
all Linux kernel version specific tools for version 4.15.0
ii linux-tools-4.15.0-55-generic 4.15.0-55.60
amd64Linux kernel version specific tools for version 4.15.0-55
A minimal series of steps necessary to make it happen
-
1. In a terminal tab., run:
$ top
2. In another tab, run
$ perf top -p `pidof top`
3. Look at the output of "perf top".
What you expected to happen
---
I expect to see "cycles" events being reported for the process "top"
(started at step 1.)
What actually happened
--
I see this, so it works:
Samples: 136 of event 'cycles:ppp', Event count (approx.): 54426558
Overhead Shared Object Symbol
8.48% libc-2.27.so[.] _IO_vfscanf
6.49% [kernel][k] do_syscall_64
4.06% [kernel][k] pid_revalidate
3.50% [kernel][k] syscall_return_via_sysret
3.05% [kernel][k] vsnprintf
2.90% [kernel][k] get_pid_task
2.88% [kernel][k] seq_put_decimal_ull
2.75% [kernel][k] __task_pid_nr_ns
2.74% [kernel][k] seq_put_decimal_ll
2.71% libc-2.27.so[.] __GI_strtoull_l_internal
2.41% [kernel][k] format_decode
2.38% [kernel][k] memcpy_erms
2.18% libc-2.27.so[.] vfprintf
1.93% [kernel][k] pid_nr_ns
1.79% [kernel][k] __d_lookup_rcu
1.63% [kernel][k] rcu_all_qs
1.58% [kernel][k] filldir
1.39% [kernel][k] render_sigset_t
System calls
perf_event_open System calls:
$ strace perf top -p `pidof top` 2>&1 | grep ^perf_event_open
perf_event_open({type=PERF_TYPE_HARDWARE, size=PERF_ATTR_SIZE_VER5,
config=PERF_COUNT_HW_CPU_CYCLES, ...}, 0, -1, -1, 0) = 3
perf_event_open({type=PERF_TYPE_SOFTWARE, size=0 /* PERF_ATTR_SIZE_??? */,
config=PERF_COUNT_SW_CPU_CLOCK, ...}, -1, 6, -1, PERF_FLAG_FD_CLOEXEC) = 3
perf_event_open({type=PERF_TYPE_HARDWARE, size=PERF_ATTR_SIZE_VER5,
config=PERF_COUNT_HW_CPU_CYCLES, ...}, -1, 0, -1, PERF_FLAG_FD_CLOEXEC) = 3
perf_event_open({type=PERF_TYPE_HARDWARE, size=PERF_ATTR_SIZE_VER5,
config=PERF_COUNT_HW_CPU_CYCLES, ...}, -1, 0, -1, PERF_FLAG_FD_CLOEXEC) = 3
perf_event_open({type=PERF_TYPE_HARDWARE, size=PERF_ATTR_SIZE_VER5,
config=PERF_COUNT_HW_CPU_CYCLES, ...}, 12089, -1, -1, PERF_FLAG_FD_CLOEXEC) = 3
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Title:
perf broken on hwe kernel 5.0.0-23
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