Hi all, I am Razya Ladelsky, I work at IBM Haifa virtualization team, which developed Elvis, presented by Abel Gordon at the last KVM forum: ELVIS video: https://www.youtube.com/watch?v=9EyweibHfEs ELVIS slides: https://drive.google.com/file/d/0BzyAwvVlQckeQmpnOHM5SnB5UVE
According to the discussions that took place at the forum, upstreaming some of the Elvis approaches seems to be a good idea, which we would like to pursue. Our plan for the first patches is the following: 1.Shared vhost thread between mutiple devices This patch creates a worker thread and worker queue shared across multiple virtio devices We would like to modify the patch posted in https://github.com/abelg/virtual_io_acceleration/commit/3dc6a3ce7bcbe87363c2df8a6b6fee0c14615766 to limit a vhost thread to serve multiple devices only if they belong to the same VM as Paolo suggested to avoid isolation or cgroups concerns. Another modification is related to the creation and removal of vhost threads, which will be discussed next. 2. Sysfs mechanism to add and remove vhost threads This patch allows us to add and remove vhost threads dynamically. A simpler way to control the creation of vhost threads is statically determining the maximum number of virtio devices per worker via a kernel module parameter (which is the way the previously mentioned patch is currently implemented) I'd like to ask for advice here about the more preferable way to go: Although having the sysfs mechanism provides more flexibility, it may be a good idea to start with a simple static parameter, and have the first patches as simple as possible. What do you think? 3.Add virtqueue polling mode to vhost Have the vhost thread poll the virtqueues with high I/O rate for new buffers , and avoid asking the guest to kick us. https://github.com/abelg/virtual_io_acceleration/commit/26616133fafb7855cc80fac070b0572fd1aaf5d0 4. vhost statistics This patch introduces a set of statistics to monitor different performance metrics of vhost and our polling and I/O scheduling mechanisms. The statistics are exposed using debugfs and can be easily displayed with a Python script (vhost_stat, based on the old kvm_stats) https://github.com/abelg/virtual_io_acceleration/commit/ac14206ea56939ecc3608dc5f978b86fa322e7b0 5. Add heuristics to improve I/O scheduling This patch enhances the round-robin mechanism with a set of heuristics to decide when to leave a virtqueue and proceed to the next. https://github.com/abelg/virtual_io_acceleration/commit/f6a4f1a5d6b82dc754e8af8af327b8d0f043dc4d This patch improves the handling of the requests by the vhost thread, but could perhaps be delayed to a later time , and not submitted as one of the first Elvis patches. I'd love to hear some comments about whether this patch needs to be part of the first submission. Any other feedback on this plan will be appreciated, Thank you, Razya -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
