linux-kernel - Re: [PATCH v2] tracing: Add verbose gfp

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Message-ID: <3062dff1-1d77-251e-253b-19c6d95d5bdc@linux.intel.com>
Date:   Fri, 12 Jul 2019 09:40:43 +0800
From:   Xing Zhengjun <zhengjun.xing@...ux.intel.com>
To:     Tom Zanussi <zanussi@...nel.org>, rostedt@...dmis.org,
        mingo@...hat.com, tom.zanussi@...ux.intel.com
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] tracing: Add verbose gfp_flag printing to synthetic
 events

Hi Tom,

On 7/11/2019 11:42 PM, Tom Zanussi wrote:
> Hi Zhengjun,
> 
> The patch itself looks fine to me, but could you please create a v3
> with a couple changes to the commit message?  I noticed you dropped
> your original commit message - please add it back and combine with part
> of mine, as below.  Also, please keep your original Subject line
> ('[PATCH] trace:add "gfp_t" support in synthetic_events') (but the
> first word after trace:, 'add', should be capitalized.)
> 
Thanks. I will send v3 version patch soon.

> On Thu, 2019-07-11 at 16:46 +0800, Zhengjun Xing wrote:
>> Add on top of 'trace:add "gfp_t" support in synthetic_events'.
> 
> Please remove this part but keep the part below.
> 
>>
>> Prints the gfp flags as hex in addition to the human-readable flag
>> string.  Example output:
>>
>>    whoopsie-630 [000] ...1 78.969452: testevent: bar=b20
>> (GFP_ATOMIC|__GFP_ZERO)
>>      rcuc/0-11  [000] ...1 81.097555: testevent: bar=a20 (GFP_ATOMIC)
>>      rcuc/0-11  [000] ...1 81.583123: testevent: bar=a20 (GFP_ATOMIC)
>>
> 
> So basically, something like this:
> 
> [PATCH] trace: Add "gfp_t" support in synthetic_events
> 
> Add "gfp_t" support in synthetic_events, then the "gfp_t" type
> parameter in some functions can be traced.
> 
> Print the gfp flags as hex in addition to the human-readable flag
> string.  Example output:
> 
>    whoopsie-630 [000] ...1 78.969452: testevent: bar=b20 (GFP_ATOMIC|__GFP_ZERO)
>      rcuc/0-11  [000] ...1 81.097555: testevent: bar=a20 (GFP_ATOMIC)
>      rcuc/0-11  [000] ...1 81.583123: testevent: bar=a20 (GFP_ATOMIC)
> 
>> Signed-off-by: Tom Zanussi <zanussi@...nel.org>
>> Signed-off-by: Zhengjun Xing <zhengjun.xing@...ux.intel.com>
> 
> 
> Thanks,
> 
> Tom
> 
>> ---
>>   kernel/trace/trace_events_hist.c | 19 +++++++++++++++++++
>>   1 file changed, 19 insertions(+)
>>
>> diff --git a/kernel/trace/trace_events_hist.c
>> b/kernel/trace/trace_events_hist.c
>> index ca6b0dff60c5..938ef3f54c5c 100644
>> --- a/kernel/trace/trace_events_hist.c
>> +++ b/kernel/trace/trace_events_hist.c
>> @@ -13,6 +13,10 @@
>>   #include <linux/rculist.h>
>>   #include <linux/tracefs.h>
>>   
>> +/* for gfp flag names */
>> +#include <linux/trace_events.h>
>> +#include <trace/events/mmflags.h>
>> +
>>   #include "tracing_map.h"
>>   #include "trace.h"
>>   #include "trace_dynevent.h"
>> @@ -752,6 +756,8 @@ static int synth_field_size(char *type)
>>   		size = sizeof(unsigned long);
>>   	else if (strcmp(type, "pid_t") == 0)
>>   		size = sizeof(pid_t);
>> +	else if (strcmp(type, "gfp_t") == 0)
>> +		size = sizeof(gfp_t);
>>   	else if (synth_field_is_string(type))
>>   		size = synth_field_string_size(type);
>>   
>> @@ -792,6 +798,8 @@ static const char *synth_field_fmt(char *type)
>>   		fmt = "%lu";
>>   	else if (strcmp(type, "pid_t") == 0)
>>   		fmt = "%d";
>> +	else if (strcmp(type, "gfp_t") == 0)
>> +		fmt = "%x";
>>   	else if (synth_field_is_string(type))
>>   		fmt = "%s";
>>   
>> @@ -834,9 +838,20 @@ static enum print_line_t
>> print_synth_event(struct trace_iterator *iter,
>>   					 i == se->n_fields - 1 ? ""
>> : " ");
>>   			n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
>>   		} else {
>> +			struct trace_print_flags __flags[] = {
>> +			    __def_gfpflag_names, {-1, NULL} };
>> +
>>   			trace_seq_printf(s, print_fmt, se-
>>> fields[i]->name,
>>   					 entry->fields[n_u64],
>>   					 i == se->n_fields - 1 ? ""
>> : " ");
>> +
>> +			if (strcmp(se->fields[i]->type, "gfp_t") ==
>> 0) {
>> +				trace_seq_puts(s, " (");
>> +				trace_print_flags_seq(s, "|",
>> +						      entry-
>>> fields[n_u64],
>> +						      __flags);
>> +				trace_seq_putc(s, ')');
>> +			}
>>   			n_u64++;
>>   		}
>>   	}

-- 
Zhengjun Xing