Re: [patch] Latency Tracer, voluntary-preempt-2.6.8-rc4-O6

Lee Revell
2004-08-13T04:58:21Z

On Thu, 2004-08-12 at 19:51, Ingo Molnar wrote:
> i've uploaded the latest version of the voluntary-preempt patch:
>
> http://redhat.com/~mingo/voluntary-preempt/voluntary-preempt-2.6.8-rc4-O6
>

Interesting results. One of the problems is kallsyms_lookup, triggered
by the printks:

0.100ms (+0.000ms): emit_log_char (printk)
0.100ms (+0.000ms): emit_log_char (printk)
0.101ms (+0.000ms): emit_log_char (printk)
0.101ms (+0.000ms): preempt_schedule (printk)
0.101ms (+0.000ms): release_console_sem (printk)
0.102ms (+0.000ms): preempt_schedule (release_console_sem)
0.102ms (+0.000ms): call_console_drivers (release_console_sem)
0.103ms (+0.000ms): _call_console_drivers (call_console_drivers)
0.103ms (+0.000ms): __call_console_drivers (call_console_drivers)
0.105ms (+0.001ms): vt_console_print (__call_console_drivers)
0.106ms (+0.001ms): vc_cons_allocated (vt_console_print)
0.108ms (+0.001ms): preempt_schedule (release_console_sem)
0.108ms (+0.000ms): __print_symbol (print_context_stack)
0.109ms (+0.001ms): kallsyms_lookup (__print_symbol)
0.491ms (+0.381ms): sprintf (__print_symbol)
0.492ms (+0.000ms): vsprintf (sprintf)
0.492ms (+0.000ms): vsnprintf (vsprintf)
0.494ms (+0.001ms): number (vsnprintf)
0.496ms (+0.001ms): number (vsnprintf)
0.497ms (+0.001ms): printk (__print_symbol)
0.497ms (+0.000ms): vscnprintf (printk)
0.497ms (+0.000ms): vsnprintf (vscnprintf)
0.499ms (+0.001ms): emit_log_char (printk)
0.499ms (+0.000ms): emit_log_char (printk)

0.778ms (+0.000ms): emit_log_char (printk)
0.779ms (+0.000ms): emit_log_char (printk)
0.779ms (+0.000ms): preempt_schedule (printk)
0.779ms (+0.000ms): release_console_sem (printk)
0.780ms (+0.000ms): preempt_schedule (release_console_sem)
0.780ms (+0.000ms): call_console_drivers (release_console_sem)
0.781ms (+0.000ms): _call_console_drivers (call_console_drivers)
0.781ms (+0.000ms): __call_console_drivers (call_console_drivers)
0.781ms (+0.000ms): vt_console_print (__call_console_drivers)
0.782ms (+0.000ms): vc_cons_allocated (vt_console_print)
0.782ms (+0.000ms): preempt_schedule (release_console_sem)
0.782ms (+0.000ms): __print_symbol (print_context_stack)
0.783ms (+0.000ms): kallsyms_lookup (__print_symbol)
1.448ms (+0.665ms): sprintf (__print_symbol)
1.448ms (+0.000ms): vsprintf (sprintf)
1.448ms (+0.000ms): vsnprintf (vsprintf)
1.450ms (+0.001ms): number (vsnprintf)
1.452ms (+0.001ms): number (vsnprintf)
1.453ms (+0.000ms): printk (__print_symbol)
1.453ms (+0.000ms): vscnprintf (printk)
1.453ms (+0.000ms): vsnprintf (vscnprintf)
1.455ms (+0.001ms): emit_log_char (printk)
1.456ms (+0.000ms): emit_log_char (printk)

Lee