Hi Eli, I'm curious as to why you want to use IVSHMEM devices in a setup like this - the whole point of IVSHMEM devices is that the same memory is shared between host and guest, such that mbufs can be passed directly between rings 'zero-copy', thus side-stepping the performance penalties inherent in memcpy.
Perhaps a vhost-user device would better suit your needs? Thanks, Mark >-----Original Message----- >From: discuss [mailto:discuss-boun...@openvswitch.org] On Behalf Of Eli >Britstein >Sent: Wednesday, March 30, 2016 3:02 PM >To: discuss@openvswitch.org >Subject: [ovs-discuss] IVSHMEM device performance > >Hi > >In a VM, I add a IVSHMEM device, on which the MBUFS mempool resides, and also >rings I create. >I saw there is a performance penalty if I use such device, instead of >hugepages (the VM's >hugepages). My VM's memory is *NOT* backed with host's hugepages. >The memory behind the IVSHMEM device is a host hugepage (patched version of >QEMU, as provided >by Intel). >I thought maybe the reason is that this memory is seen by the VM as a mapped >PCI memory >region, so it is not cached, but I am not sure. >So, my direction was to change the kernel (in the VM) so it will consider this >memory as a >regular memory (and thus cached), instead of a PCI memory region. >However, I am not sure my direction is correct, and even if so, I am not sure >how/where to >change the kernel (my starting point was mm/mmap.c, but I'm not sure it's the >correct place >to start). > >Any suggestion is welcomed. >Thanks, >Eli. >--------------------------------------------------------------------------------------------- >---------------------------------------------------- >This email and any files transmitted and/or attachments with it are >confidential and >proprietary information of >Toga Networks Ltd., and intended solely for the use of the individual or >entity to whom they >are addressed. >If you have received this email in error please notify the system manager. >This message >contains confidential >information of Toga Networks Ltd., and is intended only for the individual >named. If you are >not the named >addressee you should not disseminate, distribute or copy this e-mail. Please >notify the >sender immediately >by e-mail if you have received this e-mail by mistake and delete this e-mail >from your >system. If you are not >the intended recipient you are notified that disclosing, copying, distributing >or taking any >action in reliance on >the contents of this information is strictly prohibited. >--------------------------------------------------------------------------------------------- >--------------------------------------------------- > >_______________________________________________ >discuss mailing list >discuss@openvswitch.org >http://openvswitch.org/mailman/listinfo/discuss _______________________________________________ discuss mailing list discuss@openvswitch.org http://openvswitch.org/mailman/listinfo/discuss
