RFR(S) 8186770: NMT: Report metadata information in NMT summary

[Andrew Dinn]

On 29/08/17 15:35, Zhengyu Gu wrote:
> I struggled to come out an intuitive way for representing the numbers.
> Hopefully, we can get it right through this review process.
> 
> Actually, the formula should be:
>  committed = capacity + free chunks + available + waste

Ok, that is essentially what I computed

> capacity :   amount of all in-used chunks.
> used:        used amount out of capacity
> free chunks: amount of free chunk memory
> available:   memory that was committed, but has yet to slice into chunks.

> chunk headers are counted in *used* memory.

Ok, putting headers into the used space doesn't seem an unreasonable way
to accont for 'use'. So, that's fine -- waste is only the small regions
on the end of chunks that are not able to be used to allocate an object.

>> If so then would it not be clearer to account for this waste explicitly?
>> e.g.
>>
>>                              (  Metadata:                            )
>>                              (    reserved=22528KB,   committed=21504KB)
>>                              (    capacity=21327KB,   used=20654KB)
>>                              (    free chunks=113KB,  available=0KB)
>>                              (    waste = 560KB = 2.6%)
> 
> Make sense to report *waste*. How about
>                               (  Metadata:                            )
>                               (    reserved=22528KB,  committed=21504KB)
>                               (    capacity=21327KB,   used=20654KB)
>                               (    free chunks=113KB)
>                               (    available=0KB)
>                               (    waste = 560KB = 2.6%)
Yes, agreed except that I mentioned I think it is tidier to put free
chinks and available on the same line as I did above? Do you have a
reason for not following that suggestion?

regards,


Andrew Dinn
-----------
Senior Principal Software Engineer
Red Hat UK Ltd
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