On 05/01/2015 11:23 AM, Daniel Wagner wrote: > On 05/01/2015 02:54 AM, Steven Rostedt wrote: >> On Thu, 30 Apr 2015 21:14:52 -0500 >> Tom Zanussi <[email protected]> wrote: >> >> >>>> 'hist:key=latency.bucket:val=hitcount:sort=latency if cpu==0' >>>> >>>> but I haven't got this working. I didn't spend much time figuring out >>>> why this doesn't work. Even if the above is working you still >>> >>> I think it doesn't work because the tracepoint doesn't actually have a >>> 'cpu' field to use in the filter... >> >> Perhaps we should add special fields that don't use the tracepoint >> field, but can use generically know fields that are always known when >> the tracepoint is triggered. COMM could be one, as well as CPU.
Here a first attempt: >From fcd910836179dd738b3300dbf93a30f352e90996 Mon Sep 17 00:00:00 2001 From: Daniel Wagner <[email protected]> Date: Mon, 4 May 2015 15:44:24 +0200 Subject: [PATCH] tracing: Allow triggers to filter for CPUs By extending the filter rules by more 'generically know' fields we can write triggers filters like 'stacktrace:5 if cpu == 1' We add a new element to ftrace_common_fields which describes the new 'generically know' field. This change is visiable to user space. E.g. the format file changes for kmem:kmalloc changes to name: kmalloc ID: 395 format: field:int cpu; offset:0; size:0; signed:1; field:unsigned short common_type; offset:0; size:2; signed:0; field:unsigned char common_flags; offset:2; size:1; signed:0; field:unsigned char common_preempt_count; offset:3; size:1; signed:0; field:int common_pid; offset:4; size:4; signed:1; field:unsigned long call_site; offset:8; size:8; signed:0; field:const void * ptr; offset:16; size:8; signed:0; field:size_t bytes_req; offset:24; size:8; signed:0; field:size_t bytes_alloc; offset:32; size:8; signed:0; field:gfp_t gfp_flags; offset:40; size:4; signed:0; I think that is not complete correct since the field cpu doesn't really exists in trace event entry. Propably moving those known fields their own list is a way to overcome this problem. What do you think? And yes, I am still marveling on this comment /* If not of not match is equal to not of not, then it is a match */ from DEFINE_COMPARISON_PRED. This led me to copy it for filter_pred_cpu() :) Not for inclusion! Not-Signed-off-by: Daniel Wagner <[email protected]> --- kernel/trace/trace_events.c | 8 ++++++++ kernel/trace/trace_events_filter.c | 37 ++++++++++++++++++++++++++++++++++++- 2 files changed, 44 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index c4de47f..3f51f2b 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -144,6 +144,13 @@ int trace_define_field(struct ftrace_event_call *call, const char *type, } EXPORT_SYMBOL_GPL(trace_define_field); +#define __trace_field(type, item) \ + ret = __trace_define_field(&ftrace_common_fields, #type, \ + #item, 0, 0, is_signed_type(type), \ + FILTER_OTHER); \ + if (ret) \ + return ret; + #define __common_field(type, item) \ ret = __trace_define_field(&ftrace_common_fields, #type, \ "common_" #item, \ @@ -158,6 +165,7 @@ static int trace_define_common_fields(void) int ret; struct trace_entry ent; + __trace_field(int, cpu); __common_field(unsigned short, type); __common_field(unsigned char, flags); __common_field(unsigned char, preempt_count); diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c index ced69da..af2a6bb 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -252,6 +252,38 @@ static int filter_pred_strloc(struct filter_pred *pred, void *event) return match; } +/* Filter predicate for CPUs. */ +static int filter_pred_cpu(struct filter_pred *pred, void *event) +{ + int cpu, cmp; + int match = 0; + + cpu = raw_smp_processor_id(); + cmp = pred->val; + + switch (pred->op) { + case OP_EQ: + match = cpu == cmp; + break; + case OP_LT: + match = cpu < cmp; + break; + case OP_LE: + match = cpu <= cmp; + break; + case OP_GT: + match = cpu > cmp; + break; + case OP_GE: + match = cpu >= cmp; + break; + default: + break; + } + + return !!match == !pred->not; +} + static int filter_pred_none(struct filter_pred *pred, void *event) { return 0; @@ -1025,7 +1057,10 @@ static int init_pred(struct filter_parse_state *ps, } pred->val = val; - fn = select_comparison_fn(pred->op, field->size, + if (!strcmp(field->name, "cpu")) + fn = filter_pred_cpu; + else + fn = select_comparison_fn(pred->op, field->size, field->is_signed); if (!fn) { parse_error(ps, FILT_ERR_INVALID_OP, 0); -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
