Hi Mark, Thanks for your reply. Maybe I didn't explain well. Indeed, I use the IVSHMEM with zero-copy methodology. I don't do any packet copying. As such, I don't have any memcpy penalties (as I don't use it). Also, vhost-user device doesn't suit my needs, as I truly want a pure zero-copy system.
Thanks, Eli > -----Original Message----- > From: Kavanagh, Mark B [mailto:mark.b.kavan...@intel.com] > Sent: Wednesday, 30 March, 2016 5:07 PM > To: Eli Britstein; discuss@openvswitch.org > Subject: RE: IVSHMEM device performance > > 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 ------------------------------------------------------------------------------------------------------------------------------------------------- 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
