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author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-11-01 19:05:16 +0100 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-11-01 19:05:16 +0100 |
commit | 31f020064f9d4da5686f8dda91787f825537ad29 (patch) | |
tree | e2d8ef8fcc7d5d86a97342162a03997dac30a7d2 /Documentation | |
parent | Merge tag 'driver-core-5.10-rc2' of git://git.kernel.org/pub/scm/linux/kernel... (diff) | |
parent | Merge tag 'icc-5.10-rc2' of https://git.linaro.org/people/georgi.djakov/linux... (diff) | |
download | linux-31f020064f9d4da5686f8dda91787f825537ad29.tar.xz linux-31f020064f9d4da5686f8dda91787f825537ad29.zip |
Merge tag 'char-misc-5.10-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
Pull char/misc fixes/removals from Greg KH:
"Here's some small fixes for 5.10-rc2 and a big driver removal.
The fixes are for some reported issues in the interconnect and
coresight drivers, nothing major.
The "big" driver removal is the MIC drivers have been asked to be
removed as the hardware never shipped and Intel no longer wants to
maintain something that no one can use. This is welcomed by many as
the DMA usage of these drivers was "interesting" and the security
people were starting to question some issues that were starting to be
found in the codebase.
Note, one of the subsystems for this driver, the "VOP" code, will
probably come back in future kernel versions as it was looking to
potentially solve some PCIe virtualization issues that a number of
other vendors were wanting to solve. But as-is, this codebase didn't
work for anyone else so no actual functionality is being removed.
All of these have been in linux-next with no reported issues"
* tag 'char-misc-5.10-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
coresight: cti: Initialize dynamic sysfs attributes
coresight: Fix uninitialised pointer bug in etm_setup_aux()
coresight: add module license
misc: mic: remove the MIC drivers
interconnect: qcom: use icc_sync state for sm8[12]50
interconnect: qcom: Ensure that the floor bandwidth value is enforced
interconnect: qcom: sc7180: Init BCMs before creating the nodes
interconnect: qcom: sdm845: Init BCMs before creating the nodes
interconnect: Aggregate before setting initial bandwidth
interconnect: qcom: sdm845: Enable keepalive for the MM1 BCM
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/misc-devices/mic/index.rst | 16 | ||||
-rw-r--r-- | Documentation/misc-devices/mic/mic_overview.rst | 85 | ||||
-rw-r--r-- | Documentation/misc-devices/mic/scif_overview.rst | 108 |
3 files changed, 0 insertions, 209 deletions
diff --git a/Documentation/misc-devices/mic/index.rst b/Documentation/misc-devices/mic/index.rst deleted file mode 100644 index 3a8d06367ef1..000000000000 --- a/Documentation/misc-devices/mic/index.rst +++ /dev/null @@ -1,16 +0,0 @@ -============================================= -Intel Many Integrated Core (MIC) architecture -============================================= - -.. toctree:: - :maxdepth: 1 - - mic_overview - scif_overview - -.. only:: subproject and html - - Indices - ======= - - * :ref:`genindex` diff --git a/Documentation/misc-devices/mic/mic_overview.rst b/Documentation/misc-devices/mic/mic_overview.rst deleted file mode 100644 index 17d956bdaf7c..000000000000 --- a/Documentation/misc-devices/mic/mic_overview.rst +++ /dev/null @@ -1,85 +0,0 @@ -====================================================== -Intel Many Integrated Core (MIC) architecture overview -====================================================== - -An Intel MIC X100 device is a PCIe form factor add-in coprocessor -card based on the Intel Many Integrated Core (MIC) architecture -that runs a Linux OS. It is a PCIe endpoint in a platform and therefore -implements the three required standard address spaces i.e. configuration, -memory and I/O. The host OS loads a device driver as is typical for -PCIe devices. The card itself runs a bootstrap after reset that -transfers control to the card OS downloaded from the host driver. The -host driver supports OSPM suspend and resume operations. It shuts down -the card during suspend and reboots the card OS during resume. -The card OS as shipped by Intel is a Linux kernel with modifications -for the X100 devices. - -Since it is a PCIe card, it does not have the ability to host hardware -devices for networking, storage and console. We provide these devices -on X100 coprocessors thus enabling a self-bootable equivalent -environment for applications. A key benefit of our solution is that it -leverages the standard virtio framework for network, disk and console -devices, though in our case the virtio framework is used across a PCIe -bus. A Virtio Over PCIe (VOP) driver allows creating user space -backends or devices on the host which are used to probe virtio drivers -for these devices on the MIC card. The existing VRINGH infrastructure -in the kernel is used to access virtio rings from the host. The card -VOP driver allows card virtio drivers to communicate with their user -space backends on the host via a device page. Ring 3 apps on the host -can add, remove and configure virtio devices. A thin MIC specific -virtio_config_ops is implemented which is borrowed heavily from -previous similar implementations in lguest and s390. - -MIC PCIe card has a dma controller with 8 channels. These channels are -shared between the host s/w and the card s/w. 0 to 3 are used by host -and 4 to 7 by card. As the dma device doesn't show up as PCIe device, -a virtual bus called mic bus is created and virtual dma devices are -created on it by the host/card drivers. On host the channels are private -and used only by the host driver to transfer data for the virtio devices. - -The Symmetric Communication Interface (SCIF (pronounced as skiff)) is a -low level communications API across PCIe currently implemented for MIC. -More details are available at scif_overview.txt. - -The Coprocessor State Management (COSM) driver on the host allows for -boot, shutdown and reset of Intel MIC devices. It communicates with a COSM -"client" driver on the MIC cards over SCIF to perform these functions. - -Here is a block diagram of the various components described above. The -virtio backends are situated on the host rather than the card given better -single threaded performance for the host compared to MIC, the ability of -the host to initiate DMA's to/from the card using the MIC DMA engine and -the fact that the virtio block storage backend can only be on the host:: - - +----------+ | +----------+ - | Card OS | | | Host OS | - +----------+ | +----------+ - | - +-------+ +--------+ +------+ | +---------+ +--------+ +--------+ - | Virtio| |Virtio | |Virtio| | |Virtio | |Virtio | |Virtio | - | Net | |Console | |Block | | |Net | |Console | |Block | - | Driver| |Driver | |Driver| | |backend | |backend | |backend | - +---+---+ +---+----+ +--+---+ | +---------+ +----+---+ +--------+ - | | | | | | | - | | | |User | | | - | | | |------|------------|--+------|------- - +---------+---------+ |Kernel | - | | | - +---------+ +---+----+ +------+ | +------+ +------+ +--+---+ +-------+ - |MIC DMA | | VOP | | SCIF | | | SCIF | | COSM | | VOP | |MIC DMA| - +---+-----+ +---+----+ +--+---+ | +--+---+ +--+---+ +------+ +----+--+ - | | | | | | | - +---+-----+ +---+----+ +--+---+ | +--+---+ +--+---+ +------+ +----+--+ - |MIC | | VOP | |SCIF | | |SCIF | | COSM | | VOP | | MIC | - |HW Bus | | HW Bus| |HW Bus| | |HW Bus| | Bus | |HW Bus| |HW Bus | - +---------+ +--------+ +--+---+ | +--+---+ +------+ +------+ +-------+ - | | | | | | | - | +-----------+--+ | | | +---------------+ | - | |Intel MIC | | | | |Intel MIC | | - | |Card Driver | | | | |Host Driver | | - +---+--------------+------+ | +----+---------------+-----+ - | | | - +-------------------------------------------------------------+ - | | - | PCIe Bus | - +-------------------------------------------------------------+ diff --git a/Documentation/misc-devices/mic/scif_overview.rst b/Documentation/misc-devices/mic/scif_overview.rst deleted file mode 100644 index 4c8ad9e43706..000000000000 --- a/Documentation/misc-devices/mic/scif_overview.rst +++ /dev/null @@ -1,108 +0,0 @@ -======================================== -Symmetric Communication Interface (SCIF) -======================================== - -The Symmetric Communication Interface (SCIF (pronounced as skiff)) is a low -level communications API across PCIe currently implemented for MIC. Currently -SCIF provides inter-node communication within a single host platform, where a -node is a MIC Coprocessor or Xeon based host. SCIF abstracts the details of -communicating over the PCIe bus while providing an API that is symmetric -across all the nodes in the PCIe network. An important design objective for SCIF -is to deliver the maximum possible performance given the communication -abilities of the hardware. SCIF has been used to implement an offload compiler -runtime and OFED support for MPI implementations for MIC coprocessors. - -SCIF API Components -=================== - -The SCIF API has the following parts: - -1. Connection establishment using a client server model -2. Byte stream messaging intended for short messages -3. Node enumeration to determine online nodes -4. Poll semantics for detection of incoming connections and messages -5. Memory registration to pin down pages -6. Remote memory mapping for low latency CPU accesses via mmap -7. Remote DMA (RDMA) for high bandwidth DMA transfers -8. Fence APIs for RDMA synchronization - -SCIF exposes the notion of a connection which can be used by peer processes on -nodes in a SCIF PCIe "network" to share memory "windows" and to communicate. A -process in a SCIF node initiates a SCIF connection to a peer process on a -different node via a SCIF "endpoint". SCIF endpoints support messaging APIs -which are similar to connection oriented socket APIs. Connected SCIF endpoints -can also register local memory which is followed by data transfer using either -DMA, CPU copies or remote memory mapping via mmap. SCIF supports both user and -kernel mode clients which are functionally equivalent. - -SCIF Performance for MIC -======================== - -DMA bandwidth comparison between the TCP (over ethernet over PCIe) stack versus -SCIF shows the performance advantages of SCIF for HPC applications and -runtimes:: - - Comparison of TCP and SCIF based BW - - Throughput (GB/sec) - 8 + PCIe Bandwidth ****** - + TCP ###### - 7 + ************************************** SCIF %%%%%% - | %%%%%%%%%%%%%%%%%%% - 6 + %%%% - | %% - | %%% - 5 + %% - | %% - 4 + %% - | %% - 3 + %% - | % - 2 + %% - | %% - | % - 1 + - + ###################################### - 0 +++---+++--+--+-+--+--+-++-+--+-++-+--+-++-+- - 1 10 100 1000 10000 100000 - Transfer Size (KBytes) - -SCIF allows memory sharing via mmap(..) between processes on different PCIe -nodes and thus provides bare-metal PCIe latency. The round trip SCIF mmap -latency from the host to an x100 MIC for an 8 byte message is 0.44 usecs. - -SCIF has a user space library which is a thin IOCTL wrapper providing a user -space API similar to the kernel API in scif.h. The SCIF user space library -is distributed @ https://software.intel.com/en-us/mic-developer - -Here is some pseudo code for an example of how two applications on two PCIe -nodes would typically use the SCIF API:: - - Process A (on node A) Process B (on node B) - - /* get online node information */ - scif_get_node_ids(..) scif_get_node_ids(..) - scif_open(..) scif_open(..) - scif_bind(..) scif_bind(..) - scif_listen(..) - scif_accept(..) scif_connect(..) - /* SCIF connection established */ - - /* Send and receive short messages */ - scif_send(..)/scif_recv(..) scif_send(..)/scif_recv(..) - - /* Register memory */ - scif_register(..) scif_register(..) - - /* RDMA */ - scif_readfrom(..)/scif_writeto(..) scif_readfrom(..)/scif_writeto(..) - - /* Fence DMAs */ - scif_fence_signal(..) scif_fence_signal(..) - - mmap(..) mmap(..) - - /* Access remote registered memory */ - - /* Close the endpoints */ - scif_close(..) scif_close(..) |