Date: Thu, 11 Mar 1999 01:47:50 -0600 (CST) From: Kevin Day <toasty@home.dragondata.com> To: dillon@apollo.backplane.com (Matthew Dillon) Cc: chuckr@mat.net, peter.jeremy@AUSS2.ALCATEL.COM.AU, current@FreeBSD.ORG Subject: Re: panic: zone: entry not free Message-ID: <199903110747.BAA28636@home.dragondata.com> In-Reply-To: <199903110519.VAA61078@apollo.backplane.com> from Matthew Dillon at "Mar 10, 1999 9:19:29 pm"
next in thread | previous in thread | raw e-mail | index | archive | help
> :> :
> :> :This means that invariants need to add relatively little overhead.
> :> :
> :> :Peter
> :>
> :> .... which they do.
> :
> :You know, guys, for programmers, wanting immediate panics on stuff like
> :this is great, but there isn't one user in a thousand that wants this.
> :If you make this kinda stuff default on a version *other than* current
> :(current being by definition, for programmers/developers only) then
> :you're going to hear bloody murder, and you guys will be doing vast
> :damage to FreeBSD's reputation.
> :
> :Users don't want panics, and they don't care why, they just want things
>
> No no no... you are missing the whole point.
>
> *IF* we put these kinds of checks in by default, the result is a
> few more panics in the near term, but *NO* panics in the medium and
> long term.
>
> In otherwords, by putting the checks in now, the kernel gets debugged
> much more quickly --- to the point where a year down the line we no
> longer get kernel panics at all.
>
Also, try commenting out a panic line in a known bug, and watch how
quickly the kernel crashes anyway, in the same situation.
Most of the time, the panic is dumping out (some) debugging information
before crashing all over itself. Just taking out the diagnostic message is
really just making crashes more obscure.
If the error were recoverable, normally the system recovers from it. If it's
not, it panic's and dies. Take out the panic, and all you've got left is a
'die', which probably will lead people on a wild goose chase as to where
that section of memory really got trashed.
Kevin
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-current" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199903110747.BAA28636>