Messages in this thread | | | Date | Sun, 21 Dec 2008 13:21:12 +0100 | From | "Frédéric Weisbecker" <> | Subject | Re: [PATCH v2] tracing/function-graph-tracer: prevent from hrtimer interrupt infinite loop |
| |
2008/12/21 Ingo Molnar <mingo@elte.hu>: > > btw., a graph-tracer buglet i noticed: > > 3) | perf_counter_task_tick() { > 3) | perf_counter_task_sched_out() { > 3) | /* c:ffff88049b184000, u:0: 0000000020ca1ab0 + 0000000000000000 = 0000000020ca1ab0 > */ > 3) | /* sched-out counter ffff88049b184000, state: 0 > */ > 3) 5.024 us | } > 3) | perf_counter_task_sched_in() { > 3) | /* c:ffff88049b184000, u:0: 0000000020ca1ab0 + 0000000000000000 = 0000000020ca1ab0 > */ > 3) | /* sched-in counter ffff88049b184000, state: 1 > */ > 3) 2.605 us | } > 3) 9.714 us | } > 3) | perf_counter_task_tick() { > > the bug is that the '*/' comment closing text is printed in the next line > - that's not a linewrap, it happened like this in the trace. > > The reason is that the ftrace_printk did: > > ftrace_printk("c:%p, u:%d: %016Lx + %016Lx = %016Lx\n", > > the closing \n is pretty natural - especially for kernel hackers who might > just turn printk()s into ftrace_printk(), to embedd printouts in function > traces. So it would be nice if ftrace skipped over \n's when printing them > out as embedded C comments. > > Ingo >
Yes I was afraid of the \n from the user for these comments. You're right, I will skip the newlines from the user.
2008/12/21 Ingo Molnar <mingo@elte.hu>: > > * Ingo Molnar <mingo@elte.hu> wrote: > >> btw., a graph-tracer buglet i noticed: > > another thing. I turned off all the options that come ahead of the 'meat' > of the trace data: > > # cat /debug/tracing/trace_options > print-parent nosym-offset nosym-addr noverbose noraw nohex nobin noblock > nostacktrace nosched-tree ftrace_printk noftrace_preempt nobranch annotate > nouserstacktrace nosym-userobj printk-msg-only nofuncgraph-overrun > nofuncgraph-cpu nofuncgraph-overhead nofuncgraph-proc > > but i still got the 'duration' field printed: > > # tracer: function_graph > # > # DURATION FUNCTION CALLS > # | | | | | > > 0.865 us | } > | alloc_page_vma() { > 0.295 us | get_vma_policy(); > 0.268 us | policy_zonelist(); > | __alloc_pages_internal() { > 0.257 us | __might_sleep(); > | get_page_from_freelist() { > > > i'd have expected to only see the flow of execution as it happens. > > Ingo >
Strange. I will test that.
| |