headers that use "struct bintime"
phk at phk.freebsd.dk
Mon May 28 06:36:12 UTC 2012
In message <20120528023818.F2417 at besplex.bde.org>, Bruce Evans writes:
>devstat has silly APIs, with long double values (despite needing the
>range and precision of long doubles over doubles less than most things)
>and bintimes (despite needing the precision of bintimes over less than
>most things), but is well established so is hard to fix now.
I take it you meant to write: devstat wisely chose sufficiently
powerful data types to cover a significant of stretch of future,
rather than fall in the all too common trap of skimping on data
types for the sake of a few bytes ?
>Headers with softcs in them
>never belonged in <sys>, and softcs never belonged in public APIs,
Well, that's pretty much how ioctls worked on very early versions
of Unix, but I agree with you that it was architecturally wrong.
>I wonder why scsi is still doing so much with devstat. For disks,
>devstat handling mostly moved into geom.
Mainly because SCSI also does tapes, and non-GEOM operations, such
as formatting, on disks.
I should have severed that link when I did GEOM, splitting
devicestat into geomstat and camstat.
Doing so now would still be a good idea.
>I think libdevstat
>just uses a sysctl that converts kernel struct devicestats into
>userland struct devstat, so userland should never see the former.
It mmaps /dev/devstat, so it is slightly more tangled.
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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