Re: mbuf patch with sysctl suggestions too

On Wed, Jan 24, 2007 at 08:46:02AM -0500, Randall Stewart wrote:
Luigi Rizzo wrote:
On Tue, Jan 23, 2007 at 04:11:15PM -0500, Randall Stewart wrote:
Hi all:

Here is iteration 2 of the mbuf patch with limits I
proposed.

Also note the changes for sysctl stuff that Lugi suggested.
Please let me know what you think :-)

...
+ newnmbjclusters = nmbjumbop;
+ error = sysctl_int_checked(oidp, &newnmbjclusters, nmbjumbop,
+ SYSCTL_NO_LIMIT, req);

A few things here:
- i don't see much of a point in defining SYSCTL_NO_LIMIT;
UINT32_MAX would do perfectly there, and i think it is easier
to understand than SYSCTL_NO_LIMIT (which looks like a flag).


ok
- here and in other places you do not allow decresaing the value
(by putting min = nmbjumbop etc.), and i am not sure why.
I understand a reasonable lower bound, but i guess the worst
that can happen, when you reduce the limit to something above
the current allocation, is that nothing is allocated until
you go again below the limit, right ?

Well.. no I believe someone (was in Lin) mentioned that
you can get a live-lock if you allow a reduction.. and
thus the mbuf clusters were NOT allowed to be reduced..

maybe... but then this is definitely worth putting a note
explaining why.

cheers
luigi
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