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[PATCH 0/2] tools: Skip backward time entries
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Jiri Olsa
hi,
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. thanks, jirka --- 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(-) |
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Yonghong Song
Jiri,
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The change looks good. Could you generate a pull request against the bcc/iovisor github repository? Thanks! Yonghong On Tue, Aug 28, 2018 at 5:01 AM Jiri Olsa <jolsa@...> wrote:
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Brendan Gregg
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 Brendan On Tue, Aug 28, 2018 at 9:05 PM, Y Song <ys114321@...> wrote: Jiri, |
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