36506448d4
Reflect three changes: * Virtio now works with Linux and QEMU vhost targets * The Virtio library was separated from bdev modules * Virtio Blk bdev module has been added Change-Id: I7d3075ca863a1142b3ddcc4d18e982f3b7c72202 Signed-off-by: Dariusz Stojaczyk <dariuszx.stojaczyk@intel.com> Reviewed-on: https://review.gerrithub.io/405288 Tested-by: SPDK Automated Test System <sys_sgsw@intel.com> Reviewed-by: Pawel Wodkowski <pawelx.wodkowski@intel.com> Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com> Reviewed-by: Jim Harris <james.r.harris@intel.com>
27 lines
1.2 KiB
Markdown
27 lines
1.2 KiB
Markdown
# Virtio driver {#virtio}
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# Introduction {#virtio_intro}
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SPDK Virtio driver is a C library that allows communicating with Virtio devices.
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It allows any SPDK application to become an initiator for (SPDK) vhost targets.
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The driver supports two different usage models:
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* PCI - This is the standard mode of operation when used in a guest virtual
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machine, where QEMU has presented the virtio controller as a virtual PCI device.
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* vhost-user - Can be used to connect to a vhost socket directly on the same host.
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The driver, just like the SPDK @ref vhost, is using pollers instead of standard
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interrupts to check for an I/O response. If used inside a VM, it bypasses interrupt
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and context switching overhead of QEMU and guest kernel, significantly boosting
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the overall I/O performance.
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This Virtio library is currently used to implement two bdev modules:
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@ref bdev_config_virtio_scsi and Virtio Blk. These modules will export generic
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SPDK block devices usable by any other SPDK application.
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# Limitations {#virtio_limitations}
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Current Virtio-SCSI implementation has a couple of limitations:
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* supports only up to 8 hugepages (implies only 1GB sized pages are practical)
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* single LUN per target
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