Re: malloc_conf J j

Hi Jan,

Jan Stary wrote on Sun, May 19, 2019 at 05:46:08PM +0200:
> On May 19 16:46:44, schwarze@usta.de wrote:
>> Jan Stary wrote:

>>> The current "increase/decrease" wording in malloc(3)
>>> can suggest it has a memory. For example, setting
>>>
>>> vm.malloc_conf=J
>>>
>>> "increases" junk level to two;
>>> does setting
>>>
>>> vm.malloc_conf=C
>>>
>>> later retain a junk level of two,
>>> as there is no 'j' to "decrease" it,
>>> or is the junk level the defult of one now?

>> Your question makes no sense whatsoever.
>> First, the word "later" makes no sense.

> I should have worded more clearly. I meant programs that start later,

Oh. It didn't even occur to me that somebody could possibly fall
prey to the misconception that anything related to a library function
that is not a system call could possibly propagate from one process
to another process that isn't even a child of the first one.
I think the fact that we are in section 3 here and not in section 2
already makes it clear enough that whatever is described here starts
from scratch for every new process and cannot depend on whatever
other processes may have done before.

> after vm.malloc_conf is set to something else.

Well, sysctl(2) tells you that vm.malloc_conf is a *string*, so it
is already clear enough that the kernel does *not* store junk levels
as numbers but simply stores a string of letters. So it should be
clear that first setting one string, then another one overrides the
first string and can in no way be cumulative.

> It makes perfect sense now, thanks.

I agree nothing more seems to be missing from the documentation;
at least, i don't see what might still be missing.

Yours,
Ingo