Messages in this thread Patch in this message |  | | | Date | Fri, 10 Oct 2008 13:04:45 +0200 | | From | Ingo Molnar <> | | Subject | Re: [PATCH 1/6] Tracing/fastboot: Enable boot tracing only during initcalls |
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* Frédéric Weisbecker <fweisbec@gmail.com> wrote:
> 2008/10/10 Ingo Molnar <mingo@elte.hu>: > > > > * Frederic Weisbecker <fweisbec@gmail.com> wrote: > > > >> We used to disable the initcall tracing at a specified time (IE: end > >> of builtin initcalls). But we don\'t need it anymore. It will be > >> stopped when initcalls are finished. However we want two things: > >> > >> _Start this tracing only after pre-smp initcalls are finished. _Since > >> we are planning to trace sched_switches at the same time, we want to > >> enable them only during the initcall execution. For this purpose, this > >> patch introduce two functions to enable/disable the sched_switch > >> tracing during boot. > >> > >> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> > > > > applied to tip/tracing/fastboot, thanks Frederic! > > > > Ingo > > > > Oops, sorry Ingo there are some backslashes that taint this patch. > I will resend a V2....
dont worry, i fixed them already when i applied your patch (and that's all in latest tip/master).
See the commit below - i sanitize most commit entries to make subject lines more consistent (note the capitalization difference between your submission and the end result), to improve paragraphing and general structure.
Ingo
-----------> From d1b6be5c1bb11dfd23b000a9342b9f8c3750e143 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker <fweisbec@gmail.com> Date: Fri, 10 Oct 2008 12:36:15 +0200 Subject: [PATCH] tracing/fastboot: enable boot tracing only during initcalls We used to disable the initcall tracing at a specified time (IE: end of builtin initcalls). But we don't need it anymore. It will be stopped when initcalls are finished.
However we want two things:
_Start this tracing only after pre-smp initcalls are finished.
_Since we are planning to trace sched_switches at the same time, we want to enable them only during the initcall execution.
For this purpose, this patch introduces two functions to enable/disable the sched_switch tracing during boot.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> --- include/linux/ftrace.h | 24 ++++++++++++++++++++++-- init/main.c | 4 +++- kernel/trace/trace_boot.c | 28 ++++++++++++++++------------ 3 files changed, 41 insertions(+), 15 deletions(-) diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index a3d4615..bc9a75a 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -213,6 +213,11 @@ ftrace_init_module(unsigned long *start, unsigned long *end) { } #endif +/* + * Structure which defines the trace of an initcall. + * You don\'t have to fill the func field since it is + * only used internally by the tracer. + */ struct boot_trace { pid_t caller; char func[KSYM_NAME_LEN]; @@ -223,13 +228,28 @@ struct boot_trace { }; #ifdef CONFIG_BOOT_TRACER +/* Append the trace on the ring-buffer */ extern void trace_boot(struct boot_trace *it, initcall_t fn); + +/* Tells the tracer that smp_pre_initcall is finished. + * So we can start the tracing + */ extern void start_boot_trace(void); -extern void stop_boot_trace(void); + +/* Resume the tracing of other necessary events + * such as sched switches + */ +extern void enable_boot_trace(void); + +/* Suspend this tracing. Actually, only sched_switches tracing have + * to be suspended. Initcalls doesn\'t need it.) + */ +extern void disable_boot_trace(void); #else static inline void trace_boot(struct boot_trace *it, initcall_t fn) { } static inline void start_boot_trace(void) { } -static inline void stop_boot_trace(void) { } +static inline void enable_boot_trace(void) { } +static inline void disable_boot_trace(void) { } #endif diff --git a/init/main.c b/init/main.c index 8d58855..df48ed1 100644 --- a/init/main.c +++ b/init/main.c @@ -714,6 +714,7 @@ int do_one_initcall(initcall_t fn) it.caller = task_pid_nr(current); printk("calling %pF @ %i\n", fn, it.caller); it.calltime = ktime_get(); + enable_boot_trace(); } it.result = fn(); @@ -725,6 +726,7 @@ int do_one_initcall(initcall_t fn) printk("initcall %pF returned %d after %Ld usecs\n", fn, it.result, it.duration); trace_boot(&it, fn); + disable_boot_trace(); } msgbuf[0] = 0; @@ -957,7 +959,7 @@ static int __init kernel_init(void * unused) * we're essentially up and running. Get rid of the * initmem segments and start the user-mode stuff.. */ - stop_boot_trace(); + init_post(); return 0; } diff --git a/kernel/trace/trace_boot.c b/kernel/trace/trace_boot.c index d0a5e50..52c3743 100644 --- a/kernel/trace/trace_boot.c +++ b/kernel/trace/trace_boot.c @@ -13,23 +13,29 @@ #include "trace.h" static struct trace_array *boot_trace; -static int trace_boot_enabled; +static bool pre_initcalls_finished; - -/* Should be started after do_pre_smp_initcalls() in init/main.c */ +/* Tells the boot tracer that the pre_smp_initcalls are finished. + * So we are ready . + * It doesn\'t enable sched events tracing however. + * You have to call enable_boot_trace to do so. + */ void start_boot_trace(void) { - trace_boot_enabled = 1; + pre_initcalls_finished = true; +} + +void enable_boot_trace(void) +{ } -void stop_boot_trace(void) +void disable_boot_trace(void) { - trace_boot_enabled = 0; } void reset_boot_trace(struct trace_array *tr) { - stop_boot_trace(); + disable_boot_trace(); } static void boot_trace_init(struct trace_array *tr) @@ -37,8 +43,6 @@ static void boot_trace_init(struct trace_array *tr) int cpu; boot_trace = tr; - trace_boot_enabled = 0; - for_each_cpu_mask(cpu, cpu_possible_map) tracing_reset(tr, cpu); } @@ -46,9 +50,9 @@ static void boot_trace_init(struct trace_array *tr) static void boot_trace_ctrl_update(struct trace_array *tr) { if (tr->ctrl) - start_boot_trace(); + enable_boot_trace(); else - stop_boot_trace(); + disable_boot_trace(); } static enum print_line_t initcall_print_line(struct trace_iterator *iter) @@ -99,7 +103,7 @@ void trace_boot(struct boot_trace *it, initcall_t fn) unsigned long irq_flags; struct trace_array *tr = boot_trace; - if (!trace_boot_enabled) + if (!pre_initcalls_finished) return; /* Get its name now since this function could -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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