[PATCH 0/2] tools: Skip backward time entries
on RHEL7 we are facing timing issues in some bcc-tools
scripts. The time subsystem might return backward timestamp
via bpf_ktime_get_ns and thus screw up latency computation.
This seems to be RHEL7 kernel issue and needs to be fixed,
however meanwhile it'd be nice if affected scripts display
sane values despite the kernel issue.
This patchset harden 2 scripts (xfsslower and ext4dist)
we saw this behaviour so far, to ensure the latency is
always > 0.
Jiri Olsa (2):
tools: Skip backward time entries in xfsslower
tools: Skip backward time entries in ext4dist
tools/ext4dist.py | 10 ++++++++--
tools/xfsslower.py | 9 ++++++++-
2 files changed, 16 insertions(+), 3 deletions(-)
Jiri,toggle quoted messageShow quoted text
The change looks good. Could you generate a pull request against the
bcc/iovisor github repository?
On Tue, Aug 28, 2018 at 5:01 AM Jiri Olsa <jolsa@...> wrote:
toggle quoted messageShow quoted text
I'm ok with the workaround code, but I'd like a comment that clearly explains it for future maintainers and copy-n-pasters. Eg:
// Skip entries with backwards time: temp workaround for #728
Then people know it's a temp workaround, and they can lookup https://github.com/iovisor/bcc/issues/728
On Tue, Aug 28, 2018 at 9:05 PM, Y Song <ys114321@...> wrote: