* Maxime Coquelin (maxime.coque...@redhat.com) wrote: > Hi David, > > On 12/05/2017 06:41 PM, Dr. David Alan Gilbert wrote: > > Hi, > > Since I'm reworking the memory map update code I've been > > trying to test it with hot adding RAM; but even on upstream > > I'm finding that hot adding RAM causes the guest to stop passing > > packets with vhost-user-bridge; have either of you seen the same > > thing? > > No, I have never tried this.
Would you know if it works on dpdk? > > I'm doing: > > ./tests/vhost-user-bridge -u /tmp/vubrsrc.sock > > $QEMU -enable-kvm -m 1G,maxmem=2G,slots=4 -smp 2 -object > > memory-backend-file,id=mem,size=1G,mem-path=/dev/shm,share=on -numa > > node,memdev=mem -mem-prealloc -trace events=vhost-trace-file -chardev > > socket,id=char0,path=/tmp/vubrsrc.sock -netdev > > type=vhost-user,id=mynet1,chardev=char0,vhostforce -device > > virtio-net-pci,netdev=mynet1 $IMAGE -net none > > > > (with a f27 guest) and then doing: > > (qemu) object_add memory-backend-file,id=mem1,size=256M,mem-path=/dev/shm > > (qemu) device_add pc-dimm,id=dimm1,memdev=mem1 > > > > but then not getting any responses inside the guest. > > > > I can see the code sending another set-mem-table with the > > extra chunk of RAM and fd, and I think I can see the bridge > > mapping it. > > I think there are at least two problems. > The first one is that vhost-user-bridge does not support vhost-user > protocol's reply-ack feature. So when QEMU sends the requests, it cannot > know whether/when it has been handled by the backend. Wouldn't you have to be unlucky to cause that a problem - i.e. the descriptors would have to get allocated in the new RAM? > It had been fixed by sending a GET_FEATURE requests to be sure the > SET_MEM_TABLE was handled, as messages are processed in order. The problem > is that it caused some test failures when using TCG, so it got > reverted. > > The initial fix: > > commit 28ed5ef16384f12500abd3647973ee21b03cbe23 > Author: Prerna Saxena <prerna.sax...@nutanix.com> > Date: Fri Aug 5 03:53:51 2016 -0700 > > vhost-user: Attempt to fix a race with set_mem_table. > > The revert: > > commit 94c9cb31c04737f86be29afefbff401cd23bc24d > Author: Michael S. Tsirkin <m...@redhat.com> > Date: Mon Aug 15 16:35:24 2016 +0300 > > Revert "vhost-user: Attempt to fix a race with set_mem_table." > Do we know which tests fail? > Another problem is that memory mmapped with previous call does not seems > to be unmapped, but that should not cause other problems than leaking > virtual memory. Oh, leaks are the least of our problem there! Dave > Maxime > > Dave > > > > -- > > Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK > > -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
