Hi James,
On Thu, Apr 15, 2021 at 03:51:46PM +0300, James Clark wrote:
[...]
For the orignal perf data file with "--per-thread" option, the decoder runs into the condition for "etm->timeless_decoding"; and it doesn't contain ETM timestamp.
Afterwards, the injected perf data file also misses ETM timestamp and hit the condition "etm->timeless_decoding".
So I am confusing why the original perf data can be processed properly but fails to handle the injected perf data file.
Hi Leo,
My patch only deals with per-cpu mode. With per-thread mode everything is already working because _none_ of the events have timestamps because they are not enabled by default:
/* In per-cpu case, always need the time of mmap events etc */ if (!perf_cpu_map__empty(cpus)) evsel__set_sample_bit(tracking_evsel, TIME);
When none of the events have timestamps, I think perf doesn't use the ordering code in ordered-events.c. So when the inject file is opened, the events are read in file order.
The explination makes sense to me. One thinking: if the original file doesn't use the ordered event, is it possible for the injected file to not use the ordered event as well?
Could you confirm Intel-pt can work well for per-cpu mode for inject file?
So it's not really about --per-thread vs per-cpu mode, it's actually about whether PERF_SAMPLE_TIME is set, which is set as a by-product of per-cpu mode.
I hope I understood your question properly.
Thanks for info, sorry if I miss any info you have elaborated.
Leo