On Thu, Aug 10, 2017 at 8:51 PM, Milian Wolff <milian.wo...@kdab.com> wrote: > On Donnerstag, 10. August 2017 04:13:25 CEST Namhyung Kim wrote: >> Hi Milian, >> >> On Sun, Aug 06, 2017 at 11:24:43PM +0200, Milian Wolff wrote: >> > On one hand this ensures that the memory is properly freed when >> > the DSO gets freed. On the other hand this significantly speeds up >> > the processing of the callchain nodes when lots of srclines are >> > requested. For one of my data files e.g.: >> > >> > Before: >> > Performance counter stats for 'perf report -s srcline -g srcline -- > stdio': >> > 52496.495043 task-clock (msec) # 0.999 CPUs utilized >> > >> > 634 context-switches # 0.012 K/sec >> > >> > 2 cpu-migrations # 0.000 K/sec >> > >> > 191,561 page-faults # 0.004 M/sec >> > >> > 165,074,498,235 cycles # 3.144 GHz >> > 334,170,832,408 instructions # 2.02 insn per >> > cycle >> > >> > 90,220,029,745 branches # 1718.591 M/sec >> > >> > 654,525,177 branch-misses # 0.73% of all >> > branches >> > >> > 52.533273822 seconds time elapsedProcessed 236605 events and lost 40 >> > chunks!> >> > After: >> > Performance counter stats for 'perf report -s srcline -g srcline -- > stdio': >> > 22606.323706 task-clock (msec) # 1.000 CPUs utilized >> > >> > 31 context-switches # 0.001 K/sec >> > >> > 0 cpu-migrations # 0.000 K/sec >> > >> > 185,471 page-faults # 0.008 M/sec >> > >> > 71,188,113,681 cycles # 3.149 GHz >> > >> > 133,204,943,083 instructions # 1.87 insn per >> > cycle >> > >> > 34,886,384,979 branches # 1543.214 M/sec >> > >> > 278,214,495 branch-misses # 0.80% of all >> > branches >> > >> > 22.609857253 seconds time elapsed >> > >> > Note that the difference is only this large when `--inline` is not >> > passed. In such situations, we would use the inliner cache and >> > thus do not run this code path that often. >> > >> > I think that this cache should actually be used in other places, too. >> > When looking at the valgrind leak report for perf report, we see tons >> > of srclines being leaked, most notably from calls to >> > hist_entry__get_srcline. The problem is that get_srcline has many >> > different formatting options (show_sym, show_addr, potentially even >> > unwind_inlines when calling __get_srcline directly). As such, the >> > srcline cannot easily be cached for all calls, or we'd have to add >> > caches for all formatting combinations (6 so far). An alternative >> > would be to remove the formatting options and handle that on a >> > different level - i.e. print the sym/addr on demand wherever we >> > actually output something. And the unwind_inlines could be moved into >> > a separate function that does not return the srcline. >> >> Agreed. Also I guess no need to unwind anymore to get a srcfile for >> an entry with your change. > > Does this mean I should respin the patch series with the above changes > integrated? Or can we get this in first and then continue with the cleanup as > described above later on?
Nop, it can be done later IMHO. I will try to review the code next week. Thanks, Namhyung
