Adding upstream version 16.2.11+ds.upstream/16.2.11+dsupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

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+# What is SPDK {#about}
+
+The Storage Performance Development Kit (SPDK) provides a set of tools and
+libraries for writing high performance, scalable, user-mode storage
+applications. It achieves high performance through the use of a number of key
+techniques:
+
+* Moving all of the necessary drivers into userspace, which avoids syscalls
+  and enables zero-copy access from the application.
+* Polling hardware for completions instead of relying on interrupts, which
+  lowers both total latency and latency variance.
+* Avoiding all locks in the I/O path, instead relying on message passing.
+
+The bedrock of SPDK is a user space, polled-mode, asynchronous, lockless
+[NVMe](http://www.nvmexpress.org) driver. This provides zero-copy, highly
+parallel access directly to an SSD from a user space application. The driver is
+written as a C library with a single public header. See @ref nvme for more
+details.
+
+SPDK further provides a full block stack as a user space library that performs
+many of the same operations as a block stack in an operating system. This
+includes unifying the interface between disparate storage devices, queueing to
+handle conditions such as out of memory or I/O hangs, and logical volume
+management. See @ref bdev for more information.
+
+Finally, SPDK provides
+[NVMe-oF](http://www.nvmexpress.org/nvm-express-over-fabrics-specification-released),
+[iSCSI](https://en.wikipedia.org/wiki/ISCSI), and
+[vhost](http://blog.vmsplice.net/2011/09/qemu-internals-vhost-architecture.html)
+servers built on top of these components that are capable of serving disks over
+the network or to other processes. The standard Linux kernel initiators for
+NVMe-oF and iSCSI interoperate with these targets, as well as QEMU with vhost.
+These servers can be up to an order of magnitude more CPU efficient than other
+implementations. These targets can be used as examples of how to implement a
+high performance storage target, or used as the basis for production
+deployments.