Hello, On Mon, Mar 1, 2021 at 8:16 PM Bayduraev, Alexey V <alexey.v.baydur...@linux.intel.com> wrote: > > Hi, > > On 20.11.2020 13:49, Namhyung Kim wrote: > > On Mon, Nov 16, 2020 at 03:19:41PM +0300, Alexey Budankov wrote: > > <SNIP> > > >> > >> @@ -1400,8 +1417,12 @@ static int record__mmap_read_evlist(struct record > >> *rec, struct evlist *evlist, > >> /* > >> * Mark the round finished in case we wrote > >> * at least one event. > >> + * > >> + * No need for round events in directory mode, > >> + * because per-cpu maps and files have data > >> + * sorted by kernel. > > > > But it's not just for single cpu since task can migrate so we need to > > look at other cpu's data too. Thus we use the ordered events queue > > and round events help to determine when to flush the data. Without > > the round events, it'd consume huge amount of memory during report. > > > > If we separate tracking records and process them first, we should be > > able to process samples immediately without sorting them in the > > ordered event queue. This will save both cpu cycles and memory > > footprint significantly IMHO. > > > > Thanks, > > Namhyung > > > > As far as I understand, to split tracing records (FORK/MMAP/COMM) into > a separate file, we need to implement a runtime trace decoder on the > perf-record side to recognize such tracing records coming from the kernel. > Is that what you mean?
No, I meant separating the mmap buffers so that the record process can save the data without decoding. > > IMHO this can be tricky to implement and adds some overhead that can lead > to possible data loss. Do you have any other ideas how to optimize memory > consumption on perf-report side without a runtime trace decoder? > Maybe "round events" would somehow help in directory mode? > > BTW In our tool we use another approach: two-pass trace file loading. > The first loads tracing records, the second loads samples. Yeah, something like that. With the separated data, we can do it more efficiently IMHO. Thanks, Namhyung
