[Crash-utility] Speed up list/tree '-s' output.

[Dave Anderson]

----- Original Message -----
> Hi Dave,
> 
... [ cut ] ...
 
> The patch for crash tool can be found on github:
> https://raw.githubusercontent.com/hziSot/crash-patches/41abc6f9c91c2a602973ff9564234395deadb80e/crash_speed_up_tree_list.patch
> 
> Thanks,
> Alexandr
> 


Hi Alexandr,

A few more comments/questions regarding the -S output.

The help page descriptions of the list and tree -S options say that it does
"exactly the same thing as -s", but here are a few situations where it doesn't.

With "list -s", the parsed gdb output shows symbolic names following
a member's value in the case of direct symbol-value matches:

  crash> list file_system_type.next -s file_system_type.mount 0xffffffff819db4a0
  ffffffff819db4a0
    mount = 0xffffffff8125b7b0 <sysfs_mount>
  ffffffff819dbee0
    mount = 0xffffffff81261720 <rootfs_mount>
  ffffffff819d61a0
    mount = 0xffffffff81218f40 <bd_mount>
  ffffffff819daf40
    mount = 0xffffffff81249c60 <proc_mount>
  ffffffff8198f1c0
    mount = 0xffffffff810fb590 <cgroup_mount>
  ffffffff819904a0
    mount = 0xffffffff810fd610 <cpuset_mount>
  ffffffff819c09c0
    mount = 0xffffffff81181e50 <shmem_mount>
  ffffffff81a11860
    mount = 0xffffffff813faf40 <dev_mount>
  ffffffff819dc760
  ...

With "list -S", it shows this:

  crash> list file_system_type.next -S file_system_type.mount 0xffffffff819db4a0
  ffffffff819db4a0
    mount = 0xffffffff8125b7b0
  ffffffff819dbee0
    mount = 0xffffffff81261720
  ffffffff819d61a0
    mount = 0xffffffff81218f40
  ffffffff819daf40
    mount = 0xffffffff81249c60
  ffffffff8198f1c0
    mount = 0xffffffff810fb590
  ffffffff819904a0
    mount = 0xffffffff810fd610
  ffffffff819c09c0
  ...

Somewhat related, "list -s" will also dump ASCII strings like this:
    
  crash> list file_system_type.next -s file_system_type.name 0xffffffff819db4a0
  ffffffff819db4a0
    name = 0xffffffff8189a0f2 "sysfs"
  ffffffff819dbee0
    name = 0xffffffff8187e7cd "rootfs"
  ffffffff819d61a0
    name = 0xffffffff8187ec39 "bdev"
  ffffffff819daf40
    name = 0xffffffff8187279e "proc"
  ffffffff8198f1c0
    name = 0xffffffff81894243 "cgroup"
  ffffffff819904a0
    name = 0xffffffff81879c32 "cpuset"
  ffffffff819c09c0
    name = 0xffffffff818a63f3 "tmpfs"
  ffffffff81a11860
  ...
  
Whereas "list -S", it just shows the address:
  
  crash> list file_system_type.next -S file_system_type.name 0xffffffff819db4a0
  ffffffff819db4a0
    name = 0xffffffff8189a0f2
  ffffffff819dbee0
    name = 0xffffffff8187e7cd
  ffffffff819d61a0
    name = 0xffffffff8187ec39
  ffffffff819daf40
    name = 0xffffffff8187279e
  ffffffff8198f1c0
    name = 0xffffffff81894243
  ffffffff819904a0
    name = 0xffffffff81879c32
  ffffffff819c09c0
    name = 0xffffffff818a63f3
  ffffffff81a11860
  ...

Do you think it would be more useful to do either of the above, or would the
direct symbol-matching and/or ASCII string recognition defeat the purpose
of the -S speed-up?

And also, if no members are appended to the struct name, it doesn't show anything.
For example, with "list -s", the whole structure gets dumped when requested:
  
  crash> list file_system_type.next -s file_system_type 0xffffffff819db4a0
  ffffffff819db4a0
  struct file_system_type {
    name = 0xffffffff8189a0f2 "sysfs", 
    fs_flags = 8, 
    mount = 0xffffffff8125b7b0 <sysfs_mount>, 
    kill_sb = 0xffffffff8125b6e0 <sysfs_kill_sb>, 
    owner = 0x0, 
    next = 0xffffffff819dbee0 <rootfs_fs_type>, 
    fs_supers = {
      first = 0xffff880462a80138
    }, 
    s_lock_key = {<No data fields>}, 
    s_umount_key = {<No data fields>}, 
    s_vfs_rename_key = {<No data fields>}, 
    s_writers_key = 0xffffffff819db4d8, 
    i_lock_key = {<No data fields>}, 
    i_mutex_key = {<No data fields>}, 
    i_mutex_dir_key = {<No data fields>}
  }
  ffffffff819dbee0
  struct file_system_type {
    name = 0xffffffff8187e7cd "rootfs", 
    fs_flags = 0, 
    mount = 0xffffffff81261720 <rootfs_mount>, 
    kill_sb = 0xffffffff811e0ea0 <kill_litter_super>, 
    owner = 0x0, 
    next = 0xffffffff819d61a0 <bd_type>, 
    fs_supers = {
      first = 0xffff8804687a0938
    }, 
    s_lock_key = {<No data fields>}, 
    s_umount_key = {<No data fields>}, 
    s_vfs_rename_key = {<No data fields>}, 
    s_writers_key = 0xffffffff819dbf18, 
    i_lock_key = {<No data fields>}, 
    i_mutex_key = {<No data fields>}, 
    i_mutex_dir_key = {<No data fields>}
  }
  ffffffff819d61a0
  ...

But with -S, you just get the addresses:
  
  crash> list file_system_type.next -S file_system_type 0xffffffff819db4a0
  ffffffff819db4a0
  ffffffff819dbee0
  ffffffff819d61a0
  ffffffff819daf40
  ffffffff8198f1c0
  ffffffff819904a0
  ffffffff819c09c0
  ffffffff81a11860
  ffffffff819dc760
  ...

Should -S dump the whole structure, or should -S be specified as only
being applicable with the "struct.member[,member]" argument format?

Dave