Hi everyone, we're having some trouble getting useful results from Ftrace on OMAP3 (Gumstix Overo). As you can see in the example output below, function duration can't be displayed with a precision higher than about 30.5 us, which matches the frequency of the 32 kHz platform timer. For OMAP1, using OMAP_MPU_TIMER instead of CONFIG_OMAP_32K_TIMER should provide better results [1], but I couldn't find anything similar for OMAP3. Just setting CONFIG_OMAP_32K_TIMER=N didn't change the results. Did I miss anything, or isn't there any more precise timer?
Best regards, Thomas Klute [1] http://elinux.org/images/0/0c/Bird-LS-2009-Measuring-function-duration-with-ftrace.pdf Example Ftrace output: 876.252136 | 0) | sys_sendmsg() { 876.252166 | 0) | rom_rtadd() { 876.252197 | 0) 0.000 us | release_queue_for_dst(); 876.252197 | 0) 0.000 us | add_route(); 876.252197 | 0) + 30.517 us | } 876.252258 | 0) + 91.553 us | } -- 876.311859 | 0) | sys_sendmsg() { 876.311889 | 0) | rom_rtadd() { 876.311889 | 0) + 30.518 us | release_queue_for_dst(); 876.311920 | 0) 0.000 us | add_route(); 876.311920 | 0) + 30.518 us | } 876.311950 | 0) + 91.552 us | } -- 876.371704 | 0) | sys_sendmsg() { 876.371765 | 0) | rom_rtadd() { 876.371765 | 0) 0.000 us | release_queue_for_dst(); 876.371765 | 0) 0.000 us | add_route(); 876.371795 | 0) + 30.517 us | } 876.371826 | 0) ! 122.071 us | } -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
