Thanks Alex! Will try to reduce the memory used and check.

Anjali

From: Alex Williamson 
<alex.l.william...@gmail.com<mailto:alex.l.william...@gmail.com>>
Date: Tuesday, December 13, 2016 at 3:23 PM
To: Anjali Kulkarni <anj...@juniper.net<mailto:anj...@juniper.net>>
Cc: "vfio-users@redhat.com<mailto:vfio-users@redhat.com>" 
<vfio-users@redhat.com<mailto:vfio-users@redhat.com>>
Subject: Re: [vfio-users] Problem with vfio-pci device type and memory > 10G 
(or 8G)

On Tue, Dec 13, 2016 at 4:15 PM, Anjali Kulkarni 
<anj...@juniper.net<mailto:anj...@juniper.net>> wrote:
Thanks Alex, I think you got it, there is a lot of memory (251G), but it seems 
to be mostly all in use:

    vmstat -s

    263843488 K total memory

    254973760 K used memory


Everything looks used up?

The difference being just around 8.5G, so yeah, unless that used memory can get 
swapped out you're not going to be able to start a VM with an assigned device 
with the memory size you're looking for.  Without an assigned device the VM 
memory is not pre-allocated by default, so the resident memory for the VM might 
only be 100s of MB.  With device assignment, every page of VM memory needs to 
be allocated and mapped through the IOMMU as a potential DMA target for the 
assigned device.  There is no memory overcommit or swapping of devices making 
use of device assignment.  You're running into the Out-of-Memory killer, and 
it's never a pleasant thing.  Good luck,

Alex
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