[pcp:master] reported: boolean / quantified operations for derived-metrics #github

[pcp:master] New Comment on Issue #270 boolean / quantified operations for derived-metrics ( https://github.com/performancecopilot/pcp/issues/270 )
By wcohen ( https://github.com/wcohen ) :

Would also like to have a defined() or similar operator to determine if a particular metric is available and has numeric values. This would allow derived metrics to work around variations in the available metrics. For example newer linux kernels might have just provide a pgscan_direct entry in /proc/vmstat and not various subtypes that older kernels provided in /proc/vmstat:

mem.vmstat.pgscan_direct_all = (defined(mem.vmstat.pgscan_direct) ? mem.vmstat.pgscan_direct : mem.vmstat.pgscan_direct_dma + mem.vmstat.pgscan_direct_dma32 + mem.vmstat.pgscan_direct_dma + mem.vmstat.pgscan_direct_movable + mem.vmstat.pgscan_direct_normal)