[Virtio-fs] [RFC PATCH 1/2] virtiofsd: add stat tools

[piaojun]

On 2019/8/19 13:14, Eryu Guan wrote:
> On Mon, Aug 19, 2019 at 11:41:13AM +0800, Gang Deng wrote:
>> There exist two components: vtrace && vstat. vtrace is embeded in virtiofsd,
>> it will put raw statistics data into share memory. Then the vstat tool could
>> parse it and do some post processing works. The performance overhead of
>> vtrace is very small because it does very simple things.
>>
>> For example, if we call open(2)/close(2) frequently in guest, and
>> randwite a file whose length is greater than the size of dax window.
>> We'll get the output as below:
>>
>> op                        inflt         op/s     svctm/us   %util
>> FUSE_OPEN(14)                 0      8379.87         3.24   2.71%
>> FUSE_RELEASE(18)              0      8379.87         1.77   1.48%
>> FUSE_FLUSH(25)                0      8379.87         2.04   1.71%
>> FUSE_SETUPMAPPING(48)         1      6393.90        34.72  22.20%
>> FUSE_REMOVEMAPPING(49)        0      6404.90        37.61  24.09%
>> TOTAL                         1     37938.39        13.76  52.20%
>>
>> The meaning of fields:
>>
>> - op
>>   The type of fuse requests, 'TOTAL' is sum of all.
>>
>> - inflt
>>   The number of the inflight requests, it must be ethier 0 or 1 because
>>   virtiofsd can only process fuse requests serially.
>>
>> - op/s
>>   The number of fuse requests completed per second.
>>
>> - svctm/us
>>   The average service time (in microseconds) for fuse requests.
>>
>> - %util
>>   Percentage of elapsed time during which virtiofsd was processing the fuse
>>   requests.
>>
>> when virtiofsd is hang, e.g. we support flock in host (just for example,
>> this has been fxied), we'll get this:
>>
>> op                        inflt         op/s     svctm/us   %util
>> FUSE_SETLKW(33)               1         0.00         0.00 100.00%
>> TOTAL                         1         0.00         0.00 100.00%
>>
>> the utilization is 100% and op/s equals zero, it indicates hang.
>>
>> If virtiofsd is idle, then the output looks like this:
>>
>> op                        inflt         op/s     svctm/us   %util
>> TOTAL                         0         0.00         0.00   0.00%
>>
>> Signed-off-by: Gang Deng <gavin.dg at linux.alibaba.com>
> 
> This looks useful to me! Would you like to provide an example command
> line usage in commit log too? Because I find that it's not obvious how
> the vtrace/vstat are used.

Agreed, and I wonder if they could be documented somewhere?

Jun