usb + other drivers stop working on 128GB+ memory machines

Sun Jan 12 22:09:44 UTC 2014

On 01/10/2014 15:42, Alfred Perlstein wrote:
> Hey Alan, Neel and Hans,
>
> We're testing FreeBSD 10 here and still having problems, once we go
> over 128GB of memory then USB stops working.  When we artificially
> limit memory to 128GB or lower we are OK.
>
> Is there any chance we can revisit this patch so that large memory
> systems don't use up the lower memory space which seems to be needed
> by some drivers?
>
> I'm having a bit of trouble explaining to people that too much memory
> == no keyboard on FreeBSD.
>
> I have the patch that seemed to work for us before.  Any chance this
> can go into FreeBSD soon?
>

Sorry, I completely forgot about this issue.  If you want to file a PR
and assign it to me, that would be good.  That way, I'll get a weekly
reminder.  :-)

The only issue with this patch is that it will pessimize the speed of
physical memory allocation on amd64 machines with small amounts of
memory.  I need to augment the attached patch, which just changes some
#define's, with some changes to vm_phys.c to avoid creating excess free
page queues on small memory machines.

Alan

>
>
> -------- Original Message --------
> Subject: 	Re: Questions about FreeBSD amd64 memory layout.
> Date: 	Tue, 04 Dec 2012 00:16:08 -0800
> From: 	Alfred Perlstein <bright at mu.org>
> To: 	Alan Cox <alc at rice.edu>
> CC: 	Alan Cox <alc at FreeBSD.org>, Xin LI <delphij at delphij.net>
>
>
>
> On 12/3/12 11:23 PM, Alan Cox wrote:
> > On 12/03/2012 18:15, Alfred Perlstein wrote:
> >> Hello Alan,
> >>
> >> The other day I ran a copy of FreeBSD 9.1 with my maxusers patches
> >> (from current).
> >>
> >> The machine had 256 gigs of RAM.
> >>
> >> Due to that much memory, maxusers was upwards of 24860.
> >>
> >> What then happened was that the mfi driver, and I think also the USB
> >> driver would not work.
> >>
> >> The mfi driver stopped working because it got the following error:
> >> mfi0: Cannot allocate verbuf_h_dmamap memory
> >>
> >> This appears to be due to this in the mfi driver:
> >>>          /* Start: LSIP200113393 */
> >>>          if (bus_dma_tag_create( sc->mfi_parent_dmat,    /* parent */
> >>>                                  1, 0,                   /* algnmnt,
> >>> boundary */
> >>>                                  BUS_SPACE_MAXADDR_32BIT,/* lowaddr */
> >>>                                  BUS_SPACE_MAXADDR,      /* highaddr */
> >>>                                  NULL, NULL,             /* filter,
> >>> filterarg */
> >>> MEGASAS_MAX_NAME*sizeof(bus_addr_t),                    /* maxsize */
> >>>                                  1,                      /* msegments */
> >>> MEGASAS_MAX_NAME*sizeof(bus_addr_t),                    /* maxsegsize */
> >>>                                  0,                      /* flags */
> >>>                                  NULL, NULL,             /* lockfunc,
> >>> lockarg */
> >>>                                  &sc->verbuf_h_dmat)) {
> >>>                  device_printf(sc->mfi_dev, "Cannot allocate
> >>> verbuf_h_dmat DMA tag\n");
> >>>                  return (ENOMEM);
> >>>          }
> >>>          if (bus_dmamem_alloc(sc->verbuf_h_dmat, (void **)&sc->verbuf,
> >>>              BUS_DMA_NOWAIT, &sc->verbuf_h_dmamap)) {
> >>>                  device_printf(sc->mfi_dev, "Cannot allocate
> >>> verbuf_h_dmamap memory\n");
> >> What I'm thinking is happening is that by the time we get to mfi
> >> driver enough of the below 4GB memory is used up by callout wheels,
> >> nbufs, various hash tables, etc that we wind up unable to get memory
> >> in this region.
> >>
> >> This could (and probably is) a wrong assumption, but it's what makes
> >> sense to me right now.
> >>
> >
> > I can believe it, or more precisely I know of nothing that immediately
> > disproves it.
> >
> >   
> >> I'm wondering how the kernel map gets populated, and if it would be
> >> possible, and if it would be advisable to change the allocation
> >> strategy to come from the tail end of physical memory instead of the
> >> front.
> >>
> >
> > There is no intentional "allocation strategy" in the sense that you are
> > using the phrase here.  Much of the VM system, including the physical
> > memory allocator, is initialized early in the boot process, in fact,
> > before callout wheels, nbufs, etc. are allocated.  So, the standard
> > physical memory allocator is being used for callout wheels, nbufs, etc.,
> > and this allocator takes pages from the cache/free page queues in
> > whatever arbitrary order they happen to be in.  I can believe that we
> > currently initialize the cache/free page queues in an order that results
> > in the allocation of pages from low physical addresses first.
> >
> > The physical memory allocator does, however, have a way of dealing with
> > low physical address ranges that you don't want to allocate from except
> > explicitly, e.g., contigmalloc()/kmem_alloc_contig(), or as a last
> > resort.  This is currently only used for the physical address range for
> > ISA DMA.
> >
> > I've attached a patch that abuses the ISA DMA range, extending it to
> > 4GB.  See if this patch enables you to boot.
> >   
> >   
> It does!  Everything is fixed now.
>
> What now?  Can I help somehow?
>
> ~ % sysctl -a| grep maxuser
> kern.maxusers: 33049
> ~ % dmesg| grep mfi
> mfi0: <ThunderBolt> port 0x8000-0x80ff mem 
> 0xc7a60000-0xc7a63fff,0xc7a00000-0xc7a3ffff irq 26 at device 0.0 on pci1
> mfi0: Using MSI
> mfi0: Megaraid SAS driver Ver 4.23
> mfi0: MaxCmd = 3f0 MaxSgl = 46 state = b75003f0
> mfi0: 1436 (407894536s/0x0020/info) - Shutdown command received from host
> mfi0: 1437 (boot + 4s/0x0020/info) - Firmware initialization started 
> (PCI ID 005b/1000/0690/15d9)
> mfi0: 1438 (boot + 4s/0x0020/info) - Firmware version 3.190.05-1669
> mfi0: 1439 (boot + 5s/0x0020/info) - Package version 23.7.0-0029
> mfi0: 1440 (boot + 5s/0x0020/info) - Board Revision
> mfi0: 1441 (boot + 25s/0x0002/info) - Inserted: PD 10(e0xfc/s0)
> mfi0: 1442 (boot + 25s/0x0002/info) - Inserted: PD 10(e0xfc/s0) Info: 
> enclPd=fc, scsiType=0, portMap=00, sasAddr=4433221103000000,0000000000000000
> mfi0: 1443 (boot + 26s/0x0001/info) - Policy change on VD 00/0 to 
> [ID=00,dcp=65,ccp=64,ap=0,dc=0] from [ID=00,dcp=65,ccp=65,ap=0,dc=0]
> mfi0: 1444 (407894583s/0x0020/info) - Time established as 12/04/12 
> 0:03:03; (37 seconds since power on)
> mfi0: 1445 (407894819s/0x0020/info) - Host driver is loaded and operational
> mfid0 on mfi0
> mfid0: 2861022MB (5859373056 sectors) RAID volume (no label) is optimal
> Trying to mount root from ufs:/dev/mfid0p2 [rw]...
>
>
>