Re: [PATCH] perf tools: Exit recording if events have non matching sample type

[David Ahern <dsahern@gmail.com>]

On 10/21/2011 02:10 AM, Jiri Olsa wrote:
> On Fri, Oct 21, 2011 at 03:18:31PM +0800, Xu, Anhua wrote:
>> I installed the latest kernel and found without such patch( not sure if other patches were added besides this one). That following command works fine.
>> perf record -o perf.data -e ext3:ext3_request_inode -e LLC-loads -- date '+%F'
> hi,
> was there any ext3 event stored? The issue should be hit when
> processing stored events.. either in the atexit code or during
> report.
> 
> Following command freezes for me on 3.1.0-rc10-tip+:
> ./perf record -o perf.data -e ext4:ext4_request_inode -e LLC-loads -- date '+%F'
> 

With -B and it doesn't for me. Without the -B argument the backtrace
shows it stuck here:

#0  0x0000000000460d91 in fetch_mmaped_event (session=0x13dd510,
head=3464, mmap_size=21112,
    buf=0x7fbd1d016000 "") at util/session.c:988
#1  0x0000000000461074 in __perf_session__process_events
(session=0x13dd510, data_offset=456,
    data_size=20656, file_size=21112, ops=0x77ad40) at util/session.c:1063
#2  0x000000000041dcc4 in process_buildids () at builtin-record.c:377
#3  0x000000000041dd2e in atexit_header () at builtin-record.c:388
#4  0x0000003e96e38991 in __run_exit_handlers () from /lib64/libc.so.6
#5  0x0000003e96e38a15 in exit () from /lib64/libc.so.6
#6  0x00000000004126f8 in handle_internal_command (argc=11,
argv=0x7fffade3f3d0) at perf.c:358
#7  0x000000000041283d in run_argv (argcp=0x7fffade3f2bc,
argv=0x7fffade3f2b0) at perf.c:402
#8  0x0000000000412b24 in main (argc=11, argv=0x7fffade3f3d0) at perf.c:512


It's stuck in a loop on this:
remap:
	buf = mmap(NULL, mmap_size, mmap_prot, mmap_flags, session->fd,
		   file_offset);
	if (buf == MAP_FAILED) {
		pr_err("failed to mmap file\n");
		err = -errno;
		goto out_err;
	}
	mmaps[map_idx] = buf;
	map_idx = (map_idx + 1) & (ARRAY_SIZE(mmaps) - 1);
	file_pos = file_offset + head;

more:
	event = fetch_mmaped_event(session, head, mmap_size, buf);
	if (!event) {
		if (mmaps[map_idx]) {
			munmap(mmaps[map_idx], mmap_size);
			mmaps[map_idx] = NULL;
		}

		page_offset = page_size * (head / page_size);
		file_offset += page_offset;
		head -= page_offset;
		goto remap;
	}

head < page_size, page_offset stays 0.

David


> 
> wbr,
> jirka
> 
>>
>> -----Original Message-----
>> From: linux-kernel-owner@vger.kernel.org [mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of Jiri Olsa
>> Sent: Friday, September 30, 2011 12:01 AM
>> To: acme@redhat.com; a.p.zijlstra@chello.nl; mingo@elte.hu; paulus@samba.org
>> Cc: linux-kernel@vger.kernel.org; Jiri Olsa
>> Subject: [PATCH] perf tools: Exit recording if events have non matching sample type
>>
>> The event processing relies on all events having the same sample_type.
>>
>> This is being checked when the session is being opened read only.
>> It also needs to be checked when we do record, since events could be
>> read during processing build IDs at the end of the record command.
>>
>> If we process events with different sample_type the processing might
>> skip some events or hang.
>>
>> Following command hangs on my setup:
>>   ./perf record -o perf.data -e ext4:ext4_mb_new_group_pa \
>>    -e LLC-loads -- date '+%F'
>>
>> because hardware and tracepoint events have different sample type.
>>
>> With the patch applied the record command displays
>> "Non matching sample_type" message and exits.
>>
>> Signed-off-by: Jiri Olsa <jolsa@redhat.com>
>> ---
>>  tools/perf/builtin-record.c |    6 ++++++
>>  1 files changed, 6 insertions(+), 0 deletions(-)
>>
>> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
>> index f4c3fbe..71e2c4e 100644
>> --- a/tools/perf/builtin-record.c
>> +++ b/tools/perf/builtin-record.c
>> @@ -832,6 +832,12 @@ int cmd_record(int argc, const char **argv, const char *prefix __used)
>>  		goto out_symbol_exit;
>>  	}
>>  
>> +	if (!perf_evlist__valid_sample_type(evsel_list)) {
>> +		pr_err("Non matching sample_type\n");
>> +		err = -EINVAL;
>> +		goto out_symbol_exit;
>> +	}
>> +
>>  	if (target_pid != -1)
>>  		target_tid = target_pid;
>>  
>> -- 
>> 1.7.4
>>
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