> Subject: Re: [Patch v5 0/3] Introduce a driver to support host accelerated > access to Microsoft Azure Blob for Azure VM > > On 8/5/21 12:00 AM, longli@xxxxxxxxxxxxxxxxx wrote: > > From: Long Li <longli@xxxxxxxxxxxxx> > > > > Azure Blob storage [1] is Microsoft's object storage solution for the > > cloud. Users or client applications can access objects in Blob storage > > via HTTP, from anywhere in the world. Objects in Blob storage are > > accessible via the Azure Storage REST API, Azure PowerShell, Azure > > CLI, or an Azure Storage client library. The Blob storage interface is > > not designed to be a POSIX compliant interface. > > > > Problem: When a client accesses Blob storage via HTTP, it must go > > through the Blob storage boundary of Azure and get to the storage > > server through multiple servers. This is also true for an Azure VM. > > > > Solution: For an Azure VM, the Blob storage access can be accelerated > > by having Azure host execute the Blob storage requests to the backend > > storage server directly. > > > > This driver implements a VSC (Virtual Service Client) for accelerating > > Blob storage access for an Azure VM by communicating with a VSP > > (Virtual Service > > Provider) on the Azure host. Instead of using HTTP to access the Blob > > storage, an Azure VM passes the Blob storage request to the VSP on the > > Azure host. The Azure host uses its native network to perform Blob > > storage requests to the backend server directly. > > > > This driver doesn't implement Blob storage APIs. It acts as a fast > > channel to pass user-mode Blob storage requests to the Azure host. The > > user-mode program using this driver implements Blob storage APIs and > > packages the Blob storage request as structured data to VSC. The > > request data is modeled as three user provided buffers (request, > > response and data buffers), that are patterned on the HTTP model used > > by existing Azure Blob clients. The VSC passes those buffers to VSP for Blob > storage requests. > > > > The driver optimizes Blob storage access for an Azure VM in two ways: > > > > 1. The Blob storage requests are performed by the Azure host to the > > Azure Blob backend storage server directly. > > > > 2. It allows the Azure host to use transport technologies (e.g. RDMA) > > available to the Azure host but not available to the VM, to reach to > > Azure Blob backend servers. > > > > Test results using this driver for an Azure VM: > > 100 Blob clients running on an Azure VM, each reading 100GB Block Blobs. > > (10 TB total read data) > > With REST API over HTTP: 94.4 mins > > Using this driver: 72.5 mins > > Performance (measured in throughput) gain: 30%. > > > > [1] > > > https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdocs > > .microsoft.com%2Fen-us%2Fazure%2Fstorage%2Fblobs%2Fstorage-blobs- > intro > > > duction&data=04%7C01%7Clongli%40microsoft.com%7C6ba60a78f4e74 > aeb0b > > > b108d95833bf53%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C6376 > 378015 > > > 92577579%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoi > V2luMzIiL > > > CJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=ab5Zl2cQdmUhdT3l > SotDwMl > > DQuE0JaY%2B1REPQ0%2FjXa4%3D&reserved=0 > > Is the ioctl interface the only user space interface provided by this kernel > driver? If so, why has this code been implemented as a kernel driver instead > of e.g. a user space library that uses vfio to interact with a PCIe device? As an > example, Qemu supports many different virtio device types. The Hyper-V presents one such device for the whole VM. This device is used by all processes on the VM. (The test benchmark used 100 processes) Hyper-V doesn't support creating one device for each process. We cannot use VFIO in this model. > > Thanks, > > Bart.
