mountstats

mountstats

[Steve French]

Why are mountstats per process (e.g. "cat /proc/1/mountstats")?

The only fs which exports these appears to be nfs.   Although it is 
probably a good idea to export them for cases like nfs (and cifs and 
some clusterfs) by calling show_stats in fs/namespace.c etc.    These 
stats appear to have nothing to do with per-process data and are rather 
per-superblock.

NFS for example shows:
device localhost:/test-share mounted on /mnt with fstype nfs statvers=1.0
        opts:   
rw,vers=3,rsize=32768,wsize=32768,acregmin=3,acregmax=60,acdirmin=30,acdirmax=60,hard,proto=tcp,timeo=600,retrans=3,sec=sys 
age: 2436
        caps:   caps=0x9,wtmult=4096,dtsize=4096,bsize=0,namelen=255
        sec:    flavor=1,pseudoflavor=1
        events: 0 0 0 0 0 1 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
        bytes:  0 0 0 0 0 0 0 0
        RPC iostats version: 1.0  p/v: 100003/3 (nfs)
        xprt:   tcp 721 0 2 0 0 6 6 0 6 0
        per-op statistics
                NULL: 1 1 0 44 24 0 0 0
             GETATTR: 1 1 0 100 112 0 0 0
             SETATTR: 0 0 0 0 0 0 0 0
              LOOKUP: 1 1 0 128 116 0 0 0
              ACCESS: 1 1 0 112 120 0 0 0
            READLINK: 0 0 0 0 0 0 0 0
                READ: 0 0 0 0 0 0 0 0
               WRITE: 0 0 0 0 0 0 0 0
              CREATE: 0 0 0 0 0 0 0 0
               MKDIR: 0 0 0 0 0 0 0 0
             SYMLINK: 0 0 0 0 0 0 0 0
               MKNOD: 0 0 0 0 0 0 0 0
              REMOVE: 0 0 0 0 0 0 0 0
               RMDIR: 0 0 0 0 0 0 0 0
              RENAME: 0 0 0 0 0 0 0 0
                LINK: 0 0 0 0 0 0 0 0
             READDIR: 0 0 0 0 0 0 0 0
         READDIRPLUS: 0 0 0 0 0 0 0 0
              FSSTAT: 0 0 0 0 0 0 0 0
              FSINFO: 1 1 0 100 80 0 4 4
            PATHCONF: 0 0 0 0 0 0 0 0
              COMMIT: 0 0 0 0 0 0 0 0

Is there another path (other than read of /proc/<pid>/mounstats) which 
ends up in s_op->show_stats?

Seems logical to map cifs's /proc/fs/cifs/Stats to this as well as that 
already does per-mounted share (close enough to per-mount)
stats including:

SMBs: 6 Oplock Breaks: 0
Reads:  0 Bytes: 0
Writes: 0 Bytes: 0
Locks: 0 HardLinks: 0 Symlinks: 0
Opens: 0 Closes: 0 Deletes: 0
Mkdirs: 0 Rmdirs: 0
Renames: 0 T2 Renames 0

Re: mountstats

[Trond Myklebust]

On Tue, 2006-08-08 at 17:21 -0500, Steve French wrote:
> Why are mountstats per process (e.g. "cat /proc/1/mountstats")?

Namespaces are per-process, hence so are the per-mountpoint mountstats.

Cheers,
  Trond

Re: mountstats

[Steve French (smfltc)]

Trond Myklebust wrote:

>On Tue, 2006-08-08 at 17:21 -0500, Steve French wrote:
>  
>
>>Why are mountstats per process (e.g. "cat /proc/1/mountstats")?
>>    
>>
>
>Namespaces are per-process, hence so are the per-mountpoint mountstats.
>
>Cheers,
>  Trond
>
>  
>
Namespaces are per process but superblocks are not.  It could be 
confusing to some users. Locating
these stats [only] in the perprocess information (alongside some truly 
per-process stats) creates
the impression that the stats are those I/Os for that per-process for 
that mount while
the stats displayed are the stats for the superblock (across all 
processes that have the superblock
in the namespace).  I realize that it would not really be possible to 
show per-process/per-mount stats
but it seems odd that the per-superblock mountstats show up only here, 
rather in a more intuitive
location(s) such as /proc/mountstats [as well].

Re: mountstats

[Trond Myklebust]

On Mon, 2006-08-14 at 13:35 -0500, Steve French (smfltc) wrote:

> Namespaces are per process but superblocks are not.  It could be 
> confusing to some users. Locating
> these stats [only] in the perprocess information (alongside some truly 
> per-process stats) creates
> the impression that the stats are those I/Os for that per-process for 
> that mount while
> the stats displayed are the stats for the superblock (across all 
> processes that have the superblock
> in the namespace).  I realize that it would not really be possible to 
> show per-process/per-mount stats
> but it seems odd that the per-superblock mountstats show up only here, 
> rather in a more intuitive
> location(s) such as /proc/mountstats [as well].

I repeat: the stats are _NOT_ per superblock. They are per mountpoint.

Cheers,
  Trond