fix iteration over CPUs #908
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Since kernel version 4.9.0 BPF stopped working in a KVM guest. The problem are calls to perf_event_open with CPU identifiers which do not exist (ENODEV). The root cause for this is that the current code assumes ascending numbered CPUs. However, this is not always the case (e.g. CPU hotplugging). This patch introduces the get_online_cpus() and get_possible_cpus() helper functions and uses the appropriate function for iterations over CPUs. The BPF_MAP_TYPE_PERF_EVENT_ARRAY map contains now an entry for each possible CPU instead of for each online CPU. Fixes: iovisor#893 Signed-off-by: Andreas Gerstmayr <andreas.gerstmayr@catalysts.cc>
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Since kernel version 4.9.0 BPF stopped working in a KVM guest.
The problem are calls to perf_event_open with CPU identifiers which do
not exist (ENODEV). The root cause for this is that the current code
assumes ascending numbered CPUs. However, this is not always the case
(e.g. CPU hotplugging).
This patch introduces the get_online_cpus() and get_possible_cpus()
helper functions and uses the appropriate function for iterations over
CPUs. The BPF_PERF_OUTPUT table contains now an entry for each possible
CPU instead of for each online CPU.
Fixes #893