[DCR] Remove devstat

[Poul-Henning Kamp]

In message <1e89cd510506140433437f7b7 at mail.gmail.com>, Sue Howard writes:
>Hi,
>
>I found devstat is not widely used in the device drivers. Based the
>grep result of 'devstat_new_entry', it shows only cam, ata, fd,
>geom_disk are using it. In my workstation, the output of 'sysctl
>kern.devstat' shows:

>I am wondering if devstat can be replaced by the sysctl nodes %desc,
>%pnpinfo etc that jhb introduced. Almost all the information devstat
>can provide can be also exposed by such sysctl node.

Uhm, are we confused here ?

Devstat is what is used for collecting transaction statistics for
disks and scsi general devices in general.

Programs like iostat and gstat uses it.

The old access path (iostat) uses sysctls, but the new and practically
overhead free access path is mmap(2) which gstat uses.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
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