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10.6. Run Application and Performance ToolsNext, we run the application and take measurements using the performance tools. Because the lic filter is called directly from the GIMP, we have to use tools that can attach and monitor an already running process. In the case of oprofile, we can start oprofile, run the filter, and then stop oprofile after the filter has been completed. Because the lic filter takes up approximately 90 percent of the CPU when running, the system-wide samples that oprofile collects will be mainly relevant for the lic filter. When lic starts to run, we start oprofile in another window; when lic finishes in that other window, we stop oprofile. The starting and stopping of oprofile is shown in Listing 10.4. Listing 10.4.[root@localhost ezolt]# opcontrol --start Profiler running. [root@localhost ezolt]# opcontrol --dump [root@localhost ezolt]# opcontrol --stop Stopping profiling. ltrace must be run a little differently. After the filter has been started, ltrace can be attached to the running process. Unlike oprofile, attaching ltrace to a process brings the entire process to a crawl. This can inaccurately inflate the amount of time taken for each library call; however, it provides information about the number of times each call is made. Listing 10.5 shows a listing from ltrace. Listing 10.5.[ezolt@localhost ktracer]$ ltrace -p 32744 -c % time seconds usecs/call calls function ------ ----------- ----------- --------- -------------------- 43.61 156.419150 254 614050 rint 16.04 57.522749 281 204684 gimp_rgb_to_hsl 14.92 53.513609 261 204684 g_rand_double_range 13.88 49.793988 243 204684 gimp_rgba_set_uchar 11.55 41.426779 202 204684 gimp_pixel_rgn_get_pixel 0.00 0.006287 6287 1 gtk_widget_destroy 0.00 0.003702 3702 1 g_rand_new 0.00 0.003633 3633 1 gimp_progress_init 0.00 0.001915 1915 1 gimp_drawable_get 0.00 0.001271 1271 1 gimp_drawable_mask_bounds 0.00 0.000208 208 1 g_malloc 0.00 0.000110 110 1 gettext 0.00 0.000096 96 1 gimp_pixel_rgn_init ------ ----------- ----------- --------- -------------------- 100.00 358.693497 1432794 total To get the full number of library calls, it is possible to let ltrace run until completion; however, it takes a really long time, so in this case, we pressed <Ctrl-C> after a long period of time had elapsed. This will not always work, because an application may go through different stages of execution, and if you stop it early, you may not have a complete picture of what functions the application is calling. However, this short sample will at least give us a starting point for analysis. |
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