Messages in this thread | | | Date | Wed, 10 Jun 2009 08:18:15 -0400 (EDT) | From | Steven Rostedt <> | Subject | Re: [RFC PATCH 2/5] tracing/events: nicer print format for parsing |
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On Wed, 10 Jun 2009, Ingo Molnar wrote: > > And i kind of like the whole notion on a design level as weell: the > kernel exporting C source code for tools :-) > > Ingo > > ------------------> > > struct record { > unsigned short common_type; > unsigned char common_flags; > unsigned char common_preempt; > int common_pid; > int common_tgid; > int dev; > unsigned long long sector; > unsigned int nr_sector; > char rwbs[6]; > char comm[16]; > } this_record = { 1, 2, 3, 4, 5, 6, 7, 8, { 'a', }, "abc" }; > > void main(void) > { > struct record *REC = &this_record; > > printf("%d,%d %s %llu + %u [%s]", ((unsigned int) ((REC->dev) >> 20)), ((unsigned int) ((REC->dev) & ((1U << 20) - 1))), REC->rwbs, (unsigned long long)REC->sector, REC->nr_sector, REC->comm); > }
I actually tried this first. But it breaks once we start getting types into the code:
print fmt: "call_site=%lx ptr=%p bytes_req=%zu bytes_alloc=%zu gfp_flags=%s", REC->call_site, REC->ptr, REC->bytes_req, REC->bytes_alloc, (REC->gfp_flags) ? ({ static const struct trace_print_flags flags[] = { {(unsigned long)(((gfp_t)0x10u) | ((gfp_t)0x40u) | ((gfp_t)0x80u) | ((gfp_t)0x20000u) | ((gfp_t)0x02u) | ((gfp_t)0x100000u)), "GFP_HIGHUSER_MOVABLE"}, [...]
Will break on gfp_t. We also have cases where the enum name slips in too:
print fmt: "softirq=%d action=%s", REC->vec, ({ static const struct trace_print_flags symbols[] = { { HI_SOFTIRQ, "HI" }, { TIMER_SOFTIRQ, "TIMER" }, { NET_TX_SOFTIRQ, "NET_TX" }, { NET_RX_SOFTIRQ, "NET_RX" }, { BLOCK_SOFTIRQ, "BLOCK" }, { TASKLET_SOFTIRQ, "TASKLET" }, { SCHED_SOFTIRQ, "SCHED" }, { HRTIMER_SOFTIRQ, "HRTIMER" }, { RCU_SOFTIRQ, "RCU" }, { -1, ((void *)0) }}; ftrace_print_symbols_seq(p, REC->vec, symbols); })
Yes we can add special types for things like gfp_t, but as we get more and more users of TRACE_EVENT, the tools will never be able to keep up.
-- Steve
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