Re: 答复: Discussion about logging *Basic* statistic of evacuation failure

[Thomas Schatzl]

Hi,

On 06.12.21 12:47, lihuaming (A) wrote:
> 
>> I would like to step away from the term "Evacuation Failure" in the log messages - we will be using this mechanism for pinned region as well and I'm not really sure that using a term with "failure" in the name for something that is a regular non-exceptional occurrence.
> 
> Agree, "Evacuation Failure" is not a good option. :)
> 
>> "Remove Self Forwards" is fine.
>>
>> Here are some suggestions for the log messages:
>>
>> In-Place Evacuation (ms)        // Not sure if this is an "evacuation"
>>                                   // but "In-Place" Handling isn't really
>>                                   // good.
>>     In-Place Regions              // Maybe these three could be reported
>>                                   // in "Object Copy"? But is fine here
>>     Self Forwarded Objects        // too.
>>     In-Place Live Bytes
>>
>> "In-Place Regions" might be split later in "Pinned regions" and "Evacuation Failed Regions" (which we might use instead of "In-Place Regions" already).
> 
> Sure, we will need to distinguish between "pinned regions" and "evacuation failed regions", I think we need to do the same for objects and bytes.
> 
>> Would be nice to have "Memory Usage" for the segments/allocators too here somewhere.
> 
> Sure.
> 
>> As for the sub-phases I prefer more specific terms to generic ones like "prepare", "process", "cleanup".
>>
>>     Sort Self Forward Refs (ms)   // Also not that good probably :)
>>     Remove Self Forwards (ms)     // Actual work
>>     Reclaim Memory (ms)
> 
> Agree.
> 
> To summarize your suggestions:
> ```
> [11.094s][debug][gc,phases] GC(0)       Remove Self Forwards Total (ms): Min: 785.3, Avg: 1694.0, Max: 2515.6, Diff: 1730.4, Sum: 54209.0, Workers: 32

I kind of dislike the "Total" here - this is already indicated by the 
indentation.

> [11.094s][debug][gc,phases] GC(0)         Memory Usage Segments(bytes):      Min: xxx, Avg: xxx.8, Max: xxx, Diff: xxx, Sum: xxx, Workers: 32
> [11.094s][debug][gc,phases] GC(0)         Memory Usage Sort (bytes):      Min: xxx, Avg: xxx.8, Max: xxx, Diff: xxx, Sum: xxx, Workers: 32

Please drop the "(bytes)" unit - we do not do these for other statistics 
showing memory usage as well. It makes these identifiers shorter too.

Also something like

   Segments Memory
   Sort Memory

is just fine.

> [11.094s][debug][gc,phases] GC(0)         In-Place Regions:    Min: 79, Avg: 79.0, Max: 79, Diff: 0, Sum: 79, Workers: 1

I think at this time we can use "[Evacuation ]Failed Regions", and worry 
about the others when we're there.

> [11.094s][debug][gc,phases] GC(0)         Self Forwarded Objects:    Min: 220509, Avg: 773970.7, Max: 1188749, Diff: 968240, Sum: 24767061, Workers: 32
> [11.094s][debug][gc,phases] GC(0)         In-Place Live Bytes:      Min: 6271696, Avg: 23578654.8, Max: 36133240, Diff: 29861544, Sum: 754516952, Workers: 32

In-Place Bytes. It's obvious that they are live. Also move that one to 
trace level as it does not seem too interesting - we do not do work that 
is dependent on the memory the self-forwarded objects take.

> [11.094s][debug][gc,phases] GC(0)         Sort Self Forward Refs (ms): Min: 59.6, Avg: 231.4, Max: 363.7, Diff: 304.1, Sum: 7405.2, Workers: 32
> [11.094s][debug][gc,phases] GC(0)         Remove Self Forwards (ms): Min: 632.9, Avg: 1431.2, Max: 2145.8, Diff: 1513.0, Sum: 45799.8, Workers: 32
> [11.094s][debug][gc,phases] GC(0)         Reclaim Memory (ms): Min:  0.4, Avg:  1.7, Max:  2.8, Diff:  2.4, Sum: 52.9, Workers: 32
> ```
> 
>> But probably others have better ideas :) I will continue thinking about this.
> 
> :)

So my current suggestion is this (I reordered them a bit - typically we 
are more concerned with timing than memory consumption :P), including 
the levels (with debug level the default):

In-Place Collection (ms)            [I really do not like "Remove Self 
Forwards Total" ;)]
   Sort Self Forward Refs (ms)
   Remove Self Forwards (ms)
   Reclaim Memory (ms)               [trace, probably not interesting 
most of the time, and can be deducted by subtraction]
   Evacuation Failed Regions
   Self Forwarded Objects
   Self Forwarded Bytes              [trace]
   Segments Memory                   [trace, depending on typical size]
   Sort Memory                       [trace, depending on typical size]


We can always improve this later, so I'd maybe wait for another 
suggestion for a day or so and then let's go ahead with this.

Thanks,
   Thomas