Re: multiple issues with devstat_*(9)

On Thursday, March 31, 2011 6:33:39 pm Alexander Best wrote:
> hi there,
> 
> i think there are multiple issues with devstat. i found the following in
> devicestat.h:
> 
> /*
>  * These types are intended to aid statistics gathering/display programs.
>  * The first 13 types (up to the 'target' flag) are identical numerically
>  * to the SCSI device type numbers.  The next 3 types designate the device
>  * interface.  Currently the choices are IDE, SCSI, and 'other'.  The last
>  * flag specifies whether or not the given device is a passthrough device
>  * or not.  If it is a passthrough device, the lower 4 bits specify which
>  * type of physical device lies under the passthrough device, and the next
>  * 4 bits specify the interface.
>  */
> typedef enum {
>         DEVSTAT_TYPE_DIRECT     = 0x000,
>         DEVSTAT_TYPE_SEQUENTIAL = 0x001,
>         DEVSTAT_TYPE_PRINTER    = 0x002,
>         DEVSTAT_TYPE_PROCESSOR  = 0x003,
>         DEVSTAT_TYPE_WORM       = 0x004,
>         DEVSTAT_TYPE_CDROM      = 0x005,
>         DEVSTAT_TYPE_SCANNER    = 0x006,
>         DEVSTAT_TYPE_OPTICAL    = 0x007,
>         DEVSTAT_TYPE_CHANGER    = 0x008,
>         DEVSTAT_TYPE_COMM       = 0x009,
>         DEVSTAT_TYPE_ASC0       = 0x00a,
>         DEVSTAT_TYPE_ASC1       = 0x00b,
>         DEVSTAT_TYPE_STORARRAY  = 0x00c,
>         DEVSTAT_TYPE_ENCLOSURE  = 0x00d,
>         DEVSTAT_TYPE_FLOPPY     = 0x00e,
>         DEVSTAT_TYPE_MASK       = 0x00f,
>         DEVSTAT_TYPE_IF_SCSI    = 0x010,
>         DEVSTAT_TYPE_IF_IDE     = 0x020,
>         DEVSTAT_TYPE_IF_OTHER   = 0x030,
>         DEVSTAT_TYPE_IF_MASK    = 0x0f0,
>         DEVSTAT_TYPE_PASS       = 0x100
> } devstat_type_flags;
> 
> 
> also the devstat(9) man page says:
> 
>      Each device is given a device type.  Pass-through devices have the same
>      underlying device type and interface as the device they provide an inter-
>      face for, but they also have the pass-through flag set.  The base device
>      types are identical to the SCSI device type numbers, so with SCSI periph-
>      erals, the device type returned from an inquiry is usually ORed with the
>      SCSI interface type and the pass-through flag if appropriate.  The device
>      type flags are as follows:
> 
> ...so let's get started:
> 
> otaku% iostat -n100
>        tty            ada0             ada1              md0              cd0            pass0            pass1            pass2             cpu
>  tin  tout  KB/t tps  MB/s   KB/t tps  MB/s   KB/t tps  MB/s   KB/t tps  MB/s   KB/t tps  MB/s   KB/t tps  MB/s   KB/t tps  MB/s  us ni sy in id
>    1    92 21.18   0  0.01  24.37  12  0.29   0.00   0  0.00  60.27   0  0.01   0.37   0  0.00   0.37   0  0.00   0.00   0  0.00   5  0  4  0 90
> 
> ..so far so good
> 
> otaku% iostat -t da
>        tty            ada0             ada1              md0             cpu
>  tin  tout  KB/t tps  MB/s   KB/t tps  MB/s   KB/t tps  MB/s  us ni sy in id
>    1    92 21.18   0  0.01  24.37  12  0.29   0.00   0  0.00   5  0  4  0 90
> 
> ...not good! this should include two pass devices!

This is probably due to the hard drives being IDE (really ATA) rather than
SCSI.  I agree this should show the pass devices.

> otaku% iostat -t scsi
>        tty             cd0             cpu
>  tin  tout  KB/t tps  MB/s  us ni sy in id
>    1    92 60.27   0  0.01   5  0  4  0 90
> 
> ..what?

If cd0 is an ATAPI CD-ROM drive, then this shouldn't even show cd0 as all of
your devices are IDE/ATA, not SCSI.

> otaku% iostat -t ide
>        tty            cpu
>  tin  tout us ni sy in id
>    1    92  5  0  4  0 90
> otaku% iostat -t other
>        tty            cpu
>  tin  tout us ni sy in id
>    1    92  5  0  4  0 90
> 
> ...what about md0? ada0? ada1? md0?

md0 is a memory disk, it is neither SCSI nor IDE.  However, -t ide (or even
better, a -t ata), should show all of your other devices (adaX and cd0) along
with their passX devices I think.

> otaku% iostat -t cd0
>        tty             cd0             cpu
>  tin  tout  KB/t tps  MB/s  us ni sy in id
>    1    92 60.27   0  0.01   5  0  4  0 90
> 
> ...this should also include a pass device

Agreed.

> 
> otaku% iostat -t pass
>        tty           pass0            pass1            pass2             cpu
>  tin  tout  KB/t tps  MB/s   KB/t tps  MB/s   KB/t tps  MB/s  us ni sy in id
>    1    92  0.37   0  0.00   0.37   0  0.00   0.00   0  0.00   5  0  4  0 90
> 
> ...this one's working as expected.
> 
> funny thing is i found the following in scsi_pass.c:
> 
>         softc->device_stats = devstat_new_entry("pass",
>                           periph->unit_number, 0,
>                           DEVSTAT_NO_BLOCKSIZE
>                           | (no_tags ? DEVSTAT_NO_ORDERED_TAGS : 0),
>                           softc->pd_type |
>                           DEVSTAT_TYPE_IF_SCSI |
>                           DEVSTAT_TYPE_PASS,
>                           DEVSTAT_PRIORITY_PASS);
> 
> ...so pass* *should* show up under iostat -t scsi.

Hmm, pass devices for adaX should not be SCSI though, they should be ide I
think.

-- 
John Baldwin