svn commit: r364944 - head/sys/kern

[Mark Johnston]

On Tue, Sep 15, 2020 at 05:15:30PM +0300, Konstantin Belousov wrote:
> On Sat, Aug 29, 2020 at 04:29:53AM +0000, Warner Losh wrote:
> > Author: imp
> > Date: Sat Aug 29 04:29:53 2020
> > New Revision: 364944
> > URL: https://svnweb.freebsd.org/changeset/base/364944
> > 
> > Log:
> >   devctl: move to using a uma zone
> >   
> >   Convert the memory management of devctl.  Rewrite if to make better
> >   use of memory. This eliminates several mallocs (5? worse case) needed
> >   to send a message. It's now possible to always send a message, though
> >   if things are really backed up the oldest message will be dropped to
> >   free up space for the newest.
> >   
> >   Add a static bus_child_{location,pnpinfo}_sb to start migrating to
> >   sbuf instead of buffer + length. Use it in the new code.  Other code
> >   will be converted later (bus_child_*_str is only used inside of
> >   subr_bus.c, though implemented in ~100 places in the tree).
> >   
> >   Reviewed by: markj@
> >   Differential Revision: https://reviews.freebsd.org/D26140
> > 
> > Modified:
> >   head/sys/kern/subr_bus.c
> > 
> 
> > +	} else {
> > +		/* dei can't be NULL -- we know we have at least one in the zone */
> > +		dei = uma_zalloc(devsoftc.zone, M_NOWAIT);
> > +		MPASS(dei != NULL);
> This does not work.  I believe you need to disable per-cpu cache for the
> zone, at least.  But I am not sure it is enough.

>From the report we have:

db:0:pho>  show uma
              Zone   Size    Used    Free    Requests  Sleeps  Bucket  Total Mem    XFree
            DEVCTL   1024 6415164       0     6416203       0      16 6569127936        0

so it looks like the primary problem is a leak.

> https://people.freebsd.org/~pho/stress/log/kostik1314.txt