Hi all, We have noticed a strange thing in one of our setups which uses KVM for virtualization. The size of the buffer cache turns out to be rather large, here is what 'top' on the host has to say about it: Mem: 12274084k total, 12202860k used, 71224k free, 2991728k buffers Swap: 8191992k total, 20232k used, 8171760k free, 44392k cached As the host machine itself does not run any data intensive services, we assume that this is due to the guest VM which receives/sends about 200 GB of data per day of which about 35G have to be stored on disk (disk array connected to the host and used inside the guest via virtio). We did not run into problems with this setup, it basically runs stable for more than a year now (the buffer size never went past 30% of the total memory). However, we are not sure if the huge size of the buffer cache is something one would expect here. If this is the case, I would really love to know the reason behind it and if it has indeed something to do with KVM/virtio. Any enlightenment here would make my day. Our setup: -------------- Host: IBM BladeCenter HS22, 12 GB RAM, Xeon QC CPU CentOS 5.5 (64-bit) running 2.6.18-194.11.1.el5 kvm-83-164.el5_5.25 (qemu 0.9.1, modules 2.6.18.194.17.1) libvirt 0.6.3 Guest: Ubuntu 10.04 (64-bit) running 2.6.32-27 virtio for storage and network Best regards, -- -------------------------------------------------------------------- Martin Wawro | Digital Medics GmbH Managing Director | Otto-Hahn-Str. 15, 44227 Dortmund, Germany Tel. +49-231-9742-6622 | Fax: +49-231-9742-6623 Key: 0xB0A225BD | Registered at AG Dortmund, HRB 19360 -------------------------------------------------------------------- -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
