Extreme contigmalloc() slowness with mpt driver

Steve Kargl sgk at troutmask.apl.washington.edu
Fri Jan 13 21:53:50 PST 2006

On Sat, Jan 14, 2006 at 12:21:17AM -0500, Kris Kennaway wrote:
> I have an amd64 machine with 16GB of RAM that takes ages to boot (~40
> minutes on 7.0).  This is because the mpt driver takes 20 minutes to
> attach (with 2 instances).  This in turn is because the following code
> from dev/mpt/mpt_pci.c:mpt_dma_mem_alloc() takes about 5 seconds to
> execute, and it is run 256 times in a loop:
>                 error = bus_dmamap_create(mpt->buffer_dmat, 0, &req->dmap);
> When I set vm.old_contigmalloc=1, the system boots without delay.
> This points to a bug in contigmalloc.

This is probably related to my recent reports of extremely
slow probing of fxp0.  I have 12 GB on a Tyan K8S Pro and
fxp0 takes on the order of 7 minutes to probe.


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