Once more refactor arc_summary output

[amotin]

Before this arc_summary was not reporting any information about evictable ARC memory. As result I've found difficult to analyze behavior of dnode-heavy workload with lots of unevictable buffers.

This change adds evictable sizes into states breakdown section. While there, add/refactor sections for global memory statistics, for ARC breakdown between different structures, for data/metadata. Add information about memory reclamation requests.

While there, refactor and polish graph mode, neglected for a while.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the OpenZFS code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• I have run the ZFS Test Suite with this change applied.
• All commit messages are properly formatted and contain Signed-off-by.

[amotin]

The new output looks like this:

ARC status:
        Total memory size:                                     255.8 GiB
        Min target size:                                3.1 %    8.0 GiB
        Max target size:                               99.6 %  254.8 GiB
        Target size (adaptive):                        16.5 %   47.1 GiB
        Current size:                                  16.5 %   42.1 GiB
        Free memory size:                                      173.4 GiB
        Available memory size:                                 168.1 GiB

ARC structal breakdown (current size):                          42.1 GiB
        Compressed size:                               64.8 %   27.3 GiB
        Overhead size:                                 14.1 %    5.9 GiB
        Bonus size:                                     4.2 %    1.8 GiB
        Dnode size:                                    10.3 %    4.3 GiB
        Dbuf size:                                      4.1 %    1.7 GiB
        Header size:                                    1.0 %  414.9 MiB
        L2 header size:                                 0.0 %    0 Bytes
        ABD chunk waste size:                           1.6 %  676.6 MiB

ARC types breakdown (compressed + overhead):                    33.2 GiB
        Data size:                                     81.0 %   26.9 GiB
        Metadata size:                                 19.0 %    6.3 GiB

ARC states breakdown (compressed + overhead):                   33.2 GiB
        Anonymous data size:                            0.0 %    0 Bytes
        Anonymous metadata size:                      < 0.1 %  128.0 KiB
        MFU data target:                               37.5 %   12.4 GiB
        MFU data size:                                 37.5 %   12.4 GiB
        MFU evictable data size:                       35.2 %   11.7 GiB
        MFU ghost data size:                                     0 Bytes
        MFU metadata target:                           12.5 %    4.1 GiB
        MFU metadata size:                             17.5 %    5.8 GiB
        MFU evictable metadata size:                    1.6 %  554.8 MiB
        MFU ghost metadata size:                                 0 Bytes
        MRU data target:                               37.5 %   12.4 GiB
        MRU data size:                                 43.5 %   14.4 GiB
        MRU evictable data size:                       40.5 %   13.4 GiB
        MRU ghost data size:                                     0 Bytes
        MRU metadata target:                           12.5 %    4.1 GiB
        MRU metadata size:                              1.5 %  501.8 MiB
        MRU evictable metadata size:                    1.1 %  382.6 MiB
        MRU ghost metadata size:                                 0 Bytes
        Uncached data size:                             0.0 %    0 Bytes
        Uncached metadata size:                         0.0 %    0 Bytes

and

      ARC: 42.1 GiB (16.5 %) Data: 26.9 GiB Meta: 6.3 GiB Dnode: 4.3 GiB
    +--------------------------------------------------------------------+
    |DDDDDDDMNO                                                          |
    +--------------------------------------------------------------------+

[tonyhutter]

Merged as cdd53fe 1fdcb65