On Mon, Sep 17, 2018 at 08:40:48PM +0900, Namhyung Kim wrote: > On Thu, Sep 13, 2018 at 02:54:49PM +0200, Jiri Olsa wrote: > > Currently we assign all maps to main thread. Adding > > code that spreads maps for --threads option. > > > > For --thread option we create as many threads as there > > are memory maps in evlist, which is the number of CPUs > > in the system or CPUs we monitor. Each thread gets a > > single data mmap to read. > > > > In addition we have also same amount of tracking mmaps > > for auxiliary events which we don't create special thread > > for. Instead we assign the to the main thread, because > > there's not much traffic expected there. > > > > The assignment is visible from --thread-stats output: > > > > pid write poll skip maps (size 20K) > > 1s 9770 144B 1 0 19K 19K 19K 18K 19K > > 9772 0B 1 0 18K > > 9773 0B 1 0 19K > > 9774 0B 1 0 19K > > > > There are 5 maps for thread 9770 (1 data map and 4 auxiliary) > > and one data map for every other thread. Each thread writes > > data to the separate data file. > > Hmm.. not sure it'll work well for large machines with 1000+ cpus. > What about giving each thread a data mmap and a tracking mmap?
well currently we store the tracking data in single file, thats why we need just one thread to write them down with the *_time API, we should be able to properly read the tracking data separately for each cpu jirka
