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Re: [Qemu-devel] [PATCH] kvm: add flightrecorder script
From: |
Avi Kivity |
Subject: |
Re: [Qemu-devel] [PATCH] kvm: add flightrecorder script |
Date: |
Mon, 12 Mar 2012 14:08:10 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:10.0.1) Gecko/20120216 Thunderbird/10.0.1 |
On 03/09/2012 04:13 PM, Stefan Hajnoczi wrote:
> The kvm kernel module includes a number of trace events which can be
> useful when debugging system behavior. Even on production systems these
> trace events can be used to observe guest behavior and identify the
> source of problems.
>
> The kvm_flightrecorder script is a command-line wrapper for the
> /sys/kernel/debug/tracing interface. Kernel symbols do not need to be
> installed.
>
> This script captures a fixed-size buffer of KVM trace events. Recent
> events overwrite the oldest events when the buffer size is exceeded and
> it is possible to leave KVM tracing enabled for any period of time with
> just a fixed-size buffer. If the buffer is large enough this script is
> a useful tool for collecting detailed information after an issue occurs
> with a guest. Hence the name "flight recorder".
>
> The script can also be used in 'tail' mode to simply view KVM trace
> events as they occur. This is handy for development and to ensure that
> the guest is indeed running.
>
>
Have you considered updating trace-cmd or perf-something instead? While
each of these tools are useful we miss out on combining capabilities.
For example you could 'perf probe' a dynamic tracepoint and flightrecord
it together with kvm tracepoints.
--
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