Re: [Virtio-fs] [PATCH] virtiofsd: make the debug log timestamp on stderr more human-readable

[Laszlo Ersek <lersek@redhat.com>]

On 12/08/20 17:57, Vivek Goyal wrote:
> On Tue, Dec 08, 2020 at 06:50:43AM +0100, Laszlo Ersek wrote:
>> The current timestamp format doesn't help me visually notice small jumps
>> in time ("small" as defined on human scale, such as a few seconds or a few
>> ten seconds). Replace it with a local time format where such differences
>> stand out.
> 
> Switching to a human readable time stamp makes sense. That seems much
> more helpful for debugging, IMHO.

Thanks! (for the other review as well)
laszlo

> 
> Thanks
> Vivek
> 
>>
>> Before:
>>
>>> [13316826770337] [ID: 00000004] unique: 62, opcode: RELEASEDIR (29), nodeid: 1, insize: 64, pid: 1
>>> [13316826778175] [ID: 00000004]    unique: 62, success, outsize: 16
>>> [13316826781156] [ID: 00000004] virtio_send_msg: elem 0: with 1 in desc of length 16
>>> [15138279317927] [ID: 00000001] virtio_loop: Got VU event
>>> [15138279504884] [ID: 00000001] fv_queue_set_started: qidx=1 started=0
>>> [15138279519034] [ID: 00000003] fv_queue_thread: kill event on queue 1 - quitting
>>> [15138280876463] [ID: 00000001] fv_remove_watch: TODO! fd=9
>>> [15138280897381] [ID: 00000001] virtio_loop: Waiting for VU event
>>> [15138280946834] [ID: 00000001] virtio_loop: Got VU event
>>> [15138281175421] [ID: 00000001] virtio_loop: Waiting for VU event
>>> [15138281182387] [ID: 00000001] virtio_loop: Got VU event
>>> [15138281189474] [ID: 00000001] virtio_loop: Waiting for VU event
>>> [15138309321936] [ID: 00000001] virtio_loop: Unexpected poll revents 11
>>> [15138309434150] [ID: 00000001] virtio_loop: Exit
>>
>> (Notice how you don't (easily) notice the gap in time after
>> "virtio_send_msg", and especially the amount of time passed is hard to
>> estimate.)
>>
>> After:
>>
>>> [2020-12-08 06:43:22.58+0100] [ID: 00000004] unique: 51, opcode: RELEASEDIR (29), nodeid: 1, insize: 64, pid: 1
>>> [2020-12-08 06:43:22.58+0100] [ID: 00000004]    unique: 51, success, outsize: 16
>>> [2020-12-08 06:43:22.58+0100] [ID: 00000004] virtio_send_msg: elem 0: with 1 in desc of length 16
>>> [2020-12-08 06:43:29.34+0100] [ID: 00000001] virtio_loop: Got VU event
>>> [2020-12-08 06:43:29.34+0100] [ID: 00000001] fv_queue_set_started: qidx=1 started=0
>>> [2020-12-08 06:43:29.34+0100] [ID: 00000003] fv_queue_thread: kill event on queue 1 - quitting
>>> [2020-12-08 06:43:29.34+0100] [ID: 00000001] fv_remove_watch: TODO! fd=9
>>> [2020-12-08 06:43:29.34+0100] [ID: 00000001] virtio_loop: Waiting for VU event
>>> [2020-12-08 06:43:29.34+0100] [ID: 00000001] virtio_loop: Got VU event
>>> [2020-12-08 06:43:29.34+0100] [ID: 00000001] virtio_loop: Waiting for VU event
>>> [2020-12-08 06:43:29.34+0100] [ID: 00000001] virtio_loop: Got VU event
>>> [2020-12-08 06:43:29.34+0100] [ID: 00000001] virtio_loop: Waiting for VU event
>>> [2020-12-08 06:43:29.37+0100] [ID: 00000001] virtio_loop: Unexpected poll revents 11
>>> [2020-12-08 06:43:29.37+0100] [ID: 00000001] virtio_loop: Exit
>>
>> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>> Cc: Stefan Hajnoczi <stefanha@redhat.com>
>> Signed-off-by: Laszlo Ersek <lersek@redhat.com>
>> ---
>>  tools/virtiofsd/passthrough_ll.c | 31 +++++++++++++++++++++++++++----
>>  1 file changed, 27 insertions(+), 4 deletions(-)
>>
>> diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
>> index 48a109d3f682..06543b20dcbb 100644
>> --- a/tools/virtiofsd/passthrough_ll.c
>> +++ b/tools/virtiofsd/passthrough_ll.c
>> @@ -3311,18 +3311,38 @@ static void setup_nofile_rlimit(unsigned long rlimit_nofile)
>>  static void log_func(enum fuse_log_level level, const char *fmt, va_list ap)
>>  {
>>      g_autofree char *localfmt = NULL;
>> +    struct timespec ts;
>> +    struct tm tm;
>> +    char sec_fmt[sizeof "2020-12-07 18:17:54"];
>> +    char zone_fmt[sizeof "+0100"];
>>  
>>      if (current_log_level < level) {
>>          return;
>>      }
>>  
>>      if (current_log_level == FUSE_LOG_DEBUG) {
>> -        if (!use_syslog) {
>> -            localfmt = g_strdup_printf("[%" PRId64 "] [ID: %08ld] %s",
>> -                                       get_clock(), syscall(__NR_gettid), fmt);
>> -        } else {
>> +        if (use_syslog) {
>> +            /* no timestamp needed */
>>              localfmt = g_strdup_printf("[ID: %08ld] %s", syscall(__NR_gettid),
>>                                         fmt);
>> +        } else {
>> +            /* try formatting a broken-down timestamp */
>> +            if (clock_gettime(CLOCK_REALTIME, &ts) != -1 &&
>> +                localtime_r(&ts.tv_sec, &tm) != NULL &&
>> +                strftime(sec_fmt, sizeof sec_fmt, "%Y-%m-%d %H:%M:%S",
>> +                         &tm) != 0 &&
>> +                strftime(zone_fmt, sizeof zone_fmt, "%z", &tm) != 0) {
>> +                localfmt = g_strdup_printf("[%s.%02ld%s] [ID: %08ld] %s",
>> +                                           sec_fmt,
>> +                                           ts.tv_nsec / (10L * 1000 * 1000),
>> +                                           zone_fmt, syscall(__NR_gettid),
>> +                                           fmt);
>> +            } else {
>> +                /* fall back to a flat timestamp */
>> +                localfmt = g_strdup_printf("[%" PRId64 "] [ID: %08ld] %s",
>> +                                           get_clock(), syscall(__NR_gettid),
>> +                                           fmt);
>> +            }
>>          }
>>          fmt = localfmt;
>>      }
>> @@ -3452,6 +3472,9 @@ int main(int argc, char *argv[])
>>      struct lo_map_elem *reserve_elem;
>>      int ret = -1;
>>  
>> +    /* Initialize time conversion information for localtime_r(). */
>> +    tzset();
>> +
>>      /* Don't mask creation mode, kernel already did that */
>>      umask(0);
>>  
>> -- 
>> 2.19.1.3.g30247aa5d201
>>
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