[LITMUS^RT] trace overheads

[Björn Brandenburg]

> On 19 Sep 2016, at 12:05, shijunjie92 <shijunjie92 at gmail.com> wrote:
> 
> Hello all:
>  
> When I trying to trace the 'LOCK and UNLOCK' overheads, I add 'LOCK' and 'UNLOCK' into the 'IPI_EVENTS' of 'ft-trace-overheads’.

Why add them to IPI_EVENTS? LOCK and UNLOCK are not IPI events, no?

> But when I do the step 'ft-select-samples counts.csv combined-overheads_*.float32 2>&1 | tee -a overhead-processing.log', errors occurs '[EE] Cutoff for UNLOCK is zero.[EE] Cutoff for LOCK is zero.’. 

That means that you have some trace files that don’t contain any LOCK/UNLOCK samples; counts.csv lists 0 for these events. Please consult the source code of ft-select-samples. 

The shuffling is not needed during debugging, only once you start collecting valid data. You should debug your implementation and workflow before shuffling/subsampling traces.

- Björn