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Date: Fri, 26 Feb 2010 20:32:35 -0500 From: Steven Rostedt <rostedt@...dmis.org> To: Frederic Weisbecker <fweisbec@...il.com> Cc: LKML <linux-kernel@...r.kernel.org>, Tim Bird <tim.bird@...sony.com>, Ingo Molnar <mingo@...e.hu> Subject: [PATCH][RFC] ftrace: add tracing_thresh support to function_graph tracer (v3) Frederic, Can you take look at this patch, and if you agree, can you give it your ACK? Applying this on top of my pull request gives a nice output: [root@...hel51 tracing]# echo 300 > tracing_thresh [root@...hel51 tracing]# cat trace | head -30 # tracer: function_graph # # CPU DURATION FUNCTION CALLS # | | | | | | | 1) ! 3630.044 us | } (__dentry_open) 1) ! 3632.456 us | } (nameidata_to_filp) 1) ! 3685.980 us | } (do_filp_open) 1) ! 3701.625 us | } (do_sys_open) 1) ! 3702.830 us | } (sys_open) ------------------------------------------ 1) bash-4190 => events/-16 ------------------------------------------ 1) ! 4152.329 us | } (schedule) ------------------------------------------ 1) events/-16 => bash-4190 ------------------------------------------ 1) ! 461.230 us | } (_raw_spin_unlock_irqrestore) 1) ! 466.865 us | } (tty_ldisc_try) 1) ! 468.948 us | } (tty_ldisc_ref_wait) 0) ! 333.541 us | } (walk_tg_tree) 0) ! 339.638 us | } (update_shares) 0) ! 488.176 us | } (rebalance_domains) 0) ! 490.382 us | } (run_rebalance_domains) 0) ! 532.406 us | } (__do_softirq) 0) ! 536.246 us | } (do_softirq) 0) ! 540.842 us | } (irq_exit) 0) ! 593.286 us | } (smp_apic_timer_interrupt) (note, I forgot to update the changelog, I'll do that next) -- Steve commit c020a9a11ec44e0c81f1aa16781d2d42c6c5e560 Author: Tim Bird <tim.bird@...sony.com> Date: Thu Feb 25 15:36:43 2010 -0800 ftrace: add tracing_thresh support to function_graph tracer (v3) Add support for tracing_thresh to the function_graph tracer. This version of this feature isolates the checks into new entry and return functions, to avoid adding more conditional code into the main function_graph paths. Also, add support for specifying tracing_thresh on the kernel command line. When used like so: "tracing_thresh=200 ftrace=function_graph" this can be used to analyse system startup. It is important to disable tracing soon after boot, in order to avoid losing the trace data. Note: the elimination of 'notrace' in the definition of '__init' may be controversial. This can be removed, or made conditional, if it's a bit too scary, but it worked OK for me. Tracing during kernel startup still works, just with no visibility of routines declared __init. Signed-off-by: Tim Bird <tim.bird@...sony.com> LKML-Reference: <4B87098B.4040308@...sony.com> Signed-off-by: Steven Rostedt <rostedt@...dmis.org> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 032c57c..34ead59 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -374,6 +374,21 @@ static int __init set_buf_size(char *str) } __setup("trace_buf_size=", set_buf_size); +static int __init set_tracing_thresh(char *str) +{ + unsigned long threshhold; + int ret; + + if (!str) + return 0; + ret = strict_strtoul(str, 0, &threshhold); + if (ret < 0) + return 0; + tracing_thresh = threshhold * 1000; + return 1; +} +__setup("tracing_thresh=", set_tracing_thresh); + unsigned long nsecs_to_usecs(unsigned long nsecs) { return nsecs / 1000; @@ -579,9 +594,10 @@ static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt) static arch_spinlock_t ftrace_max_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; +unsigned long __read_mostly tracing_thresh; + #ifdef CONFIG_TRACER_MAX_TRACE unsigned long __read_mostly tracing_max_latency; -unsigned long __read_mostly tracing_thresh; /* * Copy the new maximum trace into the separate maximum-trace @@ -4248,10 +4264,10 @@ static __init int tracer_init_debugfs(void) #ifdef CONFIG_TRACER_MAX_TRACE trace_create_file("tracing_max_latency", 0644, d_tracer, &tracing_max_latency, &tracing_max_lat_fops); +#endif trace_create_file("tracing_thresh", 0644, d_tracer, &tracing_thresh, &tracing_max_lat_fops); -#endif trace_create_file("README", 0444, d_tracer, NULL, &tracing_readme_fops); diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index fd05bca..1bc8cd1 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -396,9 +396,10 @@ extern int process_new_ksym_entry(char *ksymname, int op, unsigned long addr); extern unsigned long nsecs_to_usecs(unsigned long nsecs); +extern unsigned long tracing_thresh; + #ifdef CONFIG_TRACER_MAX_TRACE extern unsigned long tracing_max_latency; -extern unsigned long tracing_thresh; void update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu); void update_max_tr_single(struct trace_array *tr, diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c index e998a82..aaf580c 100644 --- a/kernel/trace/trace_functions_graph.c +++ b/kernel/trace/trace_functions_graph.c @@ -237,6 +237,14 @@ int trace_graph_entry(struct ftrace_graph_ent *trace) return ret; } +int trace_graph_thresh_entry(struct ftrace_graph_ent *trace) +{ + if (tracing_thresh) + return 1; + else + return trace_graph_entry(trace); +} + static void __trace_graph_return(struct trace_array *tr, struct ftrace_graph_ret *trace, unsigned long flags, @@ -290,13 +298,26 @@ void set_graph_array(struct trace_array *tr) smp_mb(); } +void trace_graph_thresh_return(struct ftrace_graph_ret *trace) +{ + if (tracing_thresh && + (trace->rettime - trace->calltime < tracing_thresh)) + return; + else + trace_graph_return(trace); +} + static int graph_trace_init(struct trace_array *tr) { int ret; set_graph_array(tr); - ret = register_ftrace_graph(&trace_graph_return, - &trace_graph_entry); + if (tracing_thresh) + ret = register_ftrace_graph(&trace_graph_thresh_return, + &trace_graph_thresh_entry); + else + ret = register_ftrace_graph(&trace_graph_return, + &trace_graph_entry); if (ret) return ret; tracing_start_cmdline_record(); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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