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? Thanks, Namhyung > > In addition we also pin every thread to the cpu that > the data map belongs to in order to keep both writer > (kernel) and reader (perf tool thread) on the same CPU. > > Link: http://lkml.kernel.org/n/[email protected] > Signed-off-by: Jiri Olsa <[email protected]>
