Date: Wed, 25 May 2016 07:14:52 +0000 (UTC) From: Alexander Motin <mav@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Subject: svn commit: r300663 - stable/10/share/man/man4 Message-ID: <201605250714.u4P7EqhX021703@repo.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: mav Date: Wed May 25 07:14:52 2016 New Revision: 300663 URL: https://svnweb.freebsd.org/changeset/base/300663 Log: Add ioat.4 missed in r300661. Added: stable/10/share/man/man4/ioat.4 (contents, props changed) Added: stable/10/share/man/man4/ioat.4 ============================================================================== --- /dev/null 00:00:00 1970 (empty, because file is newly added) +++ stable/10/share/man/man4/ioat.4 Wed May 25 07:14:52 2016 (r300663) @@ -0,0 +1,334 @@ +.\" Copyright (c) 2015 EMC / Isilon Storage Division +.\" All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" $FreeBSD$ +.\" +.Dd May 3, 2016 +.Dt IOAT 4 +.Os +.Sh NAME +.Nm I/OAT +.Nd Intel I/O Acceleration Technology +.Sh SYNOPSIS +To compile this driver into your kernel, +place the following line in your kernel configuration file: +.Bd -ragged -offset indent +.Cd "device ioat" +.Ed +.Pp +Or, to load the driver as a module at boot, place the following line in +.Xr loader.conf 5 : +.Bd -literal -offset indent +ioat_load="YES" +.Ed +.Pp +In +.Xr loader.conf 5 : +.Pp +.Cd hw.ioat.force_legacy_interrupts=0 +.Pp +In +.Xr loader.conf 5 or +.Xr sysctl.conf 5 : +.Pp +.Cd hw.ioat.enable_ioat_test=0 +.Cd hw.ioat.debug_level=0 +(only critical errors; maximum of 3) +.Pp +.Ft typedef void +.Fn (*bus_dmaengine_callback_t) "void *arg" "int error" +.Pp +.Ft bus_dmaengine_t +.Fn ioat_get_dmaengine "uint32_t channel_index" +.Ft void +.Fn ioat_put_dmaengine "bus_dmaengine_t dmaengine" +.Ft int +.Fn ioat_get_hwversion "bus_dmaengine_t dmaengine" +.Ft size_t +.Fn ioat_get_max_io_size "bus_dmaengine_t dmaengine" +.Ft int +.Fn ioat_set_interrupt_coalesce "bus_dmaengine_t dmaengine" "uint16_t delay" +.Ft uint16_t +.Fn ioat_get_max_coalesce_period "bus_dmaengine_t dmaengine" +.Ft void +.Fn ioat_acquire "bus_dmaengine_t dmaengine" +.Ft int +.Fn ioat_acquire_reserve "bus_dmaengine_t dmaengine" "uint32_t n" "int mflags" +.Ft void +.Fn ioat_release "bus_dmaengine_t dmaengine" +.Ft struct bus_dmadesc * +.Fo ioat_copy +.Fa "bus_dmaengine_t dmaengine" +.Fa "bus_addr_t dst" +.Fa "bus_addr_t src" +.Fa "bus_size_t len" +.Fa "bus_dmaengine_callback_t callback_fn" +.Fa "void *callback_arg" +.Fa "uint32_t flags" +.Fc +.Ft struct bus_dmadesc * +.Fo ioat_copy_8k_aligned +.Fa "bus_dmaengine_t dmaengine" +.Fa "bus_addr_t dst1" +.Fa "bus_addr_t dst2" +.Fa "bus_addr_t src1" +.Fa "bus_addr_t src2" +.Fa "bus_dmaengine_callback_t callback_fn" +.Fa "void *callback_arg" +.Fa "uint32_t flags" +.Fc +.Ft struct bus_dmadesc * +.Fo ioat_copy_crc +.Fa "bus_dmaengine_t dmaengine" +.Fa "bus_addr_t dst" +.Fa "bus_addr_t src" +.Fa "bus_size_t len" +.Fa "uint32_t *initialseed" +.Fa "bus_addr_t crcptr" +.Fa "bus_dmaengine_callback_t callback_fn" +.Fa "void *callback_arg" +.Fa "uint32_t flags" +.Fc +.Ft struct bus_dmadesc * +.Fo ioat_crc +.Fa "bus_dmaengine_t dmaengine" +.Fa "bus_addr_t src" +.Fa "bus_size_t len" +.Fa "uint32_t *initialseed" +.Fa "bus_addr_t crcptr" +.Fa "bus_dmaengine_callback_t callback_fn" +.Fa "void *callback_arg" +.Fa "uint32_t flags" +.Fc +.Ft struct bus_dmadesc * +.Fo ioat_blockfill +.Fa "bus_dmaengine_t dmaengine" +.Fa "bus_addr_t dst" +.Fa "uint64_t fillpattern" +.Fa "bus_size_t len" +.Fa "bus_dmaengine_callback_t callback_fn" +.Fa "void *callback_arg" +.Fa "uint32_t flags" +.Fc +.Ft struct bus_dmadesc * +.Fo ioat_null +.Fa "bus_dmaengine_t dmaengine" +.Fa "bus_dmaengine_callback_t callback_fn" +.Fa "void *callback_arg" +.Fa "uint32_t flags" +.Fc +.Sh DESCRIPTION +The +.Nm +driver provides a kernel API to a variety of DMA engines on some Intel server +platforms. +.Pp +There is a number of DMA channels per CPU package. +(Typically 4 or 8.) +Each may be used independently. +Operations on a single channel proceed sequentially. +.Pp +Blockfill operations can be used to write a 64-bit pattern to memory. +.Pp +Copy operations can be used to offload memory copies to the DMA engines. +.Pp +Null operations do nothing, but may be used to test the interrupt and callback +mechanism. +.Pp +All operations can optionally trigger an interrupt at completion with the +.Ar DMA_INT_EN +flag. +For example, a user might submit multiple operations to the same channel and +only enable an interrupt and callback for the last operation. +.Pp +The hardware can delay and coalesce interrupts on a given channel for a +configurable period of time, in microseconds. +This may be desired to reduce the processing and interrupt overhead per +descriptor, especially for workflows consisting of many small operations. +Software can control this on a per-channel basis with the +.Fn ioat_set_interrupt_coalesce +API. +The +.Fn ioat_get_max_coalesce_period +API can be used to determine the maximum coalescing period supported by the +hardware, in microseconds. +Current platforms support up to a 16.383 millisecond coalescing period. +Optimal configuration will vary by workflow and desired operation latency. +.Pp +All operations are safe to use in a non-blocking context with the +.Ar DMA_NO_WAIT +flag. +(Of course, allocations may fail and operations requested with +.Ar DMA_NO_WAIT +may return NULL.) +.Pp +Operations that depend on the result of prior operations should use +.Ar DMA_FENCE . +For example, such a scenario can happen when two related DMA operations are +queued. +First, a DMA copy to one location (A), followed directly by a DMA copy +from A to B. +In this scenario, some classes of I/OAT hardware may prefetch A for the second +operation before it is written by the first operation. +To avoid reading a stale value in sequences of dependent operations, use +.Ar DMA_FENCE . +.Pp +All operations, as well as +.Fn ioat_get_dmaengine , +can return NULL in special circumstances. +For example, if the +.Nm +driver is being unloaded, or the administrator has induced a hardware reset, or +a usage error has resulted in a hardware error state that needs to be recovered +from. +.Pp +It is invalid to attempt to submit new DMA operations in a +.Fa bus_dmaengine_callback_t +context. +.Pp +The CRC operations have three distinct modes. +The default mode is to accumulate. +By accumulating over multiple descriptors, a user may gather a CRC over several +chunks of memory and only write out the result once. +.Pp +The +.Ar DMA_CRC_STORE +flag causes the operation to emit the CRC32C result. +If +.Ar DMA_CRC_INLINE +is set, the result is written inline with the destination data (or source in +.Fn ioat_crc +mode). +If +.Ar DMA_CRC_INLINE +is not set, the result is written to the provided +.Fa crcptr . +.Pp +Similarly, the +.Ar DMA_CRC_TEST +flag causes the operation to compare the CRC32C result to an existing checksum. +If +.Ar DMA_CRC_INLINE +is set, the result is compared against the inline four bytes trailing the +source data. +If it is not set, the result is compared against the value pointed to by +.Fa crcptr . +.Pp +.Fn ioat_copy_crc +calculates a CRC32C while copying data. +.Fn ioat_crc +only computes a CRC32C of some data. +If the +.Fa initialseed +argument to either routine is non-NULL, the CRC32C engine is initialized with +the value it points to. +.Sh USAGE +A typical user will lookup the DMA engine object for a given channel with +.Fn ioat_get_dmaengine . +When the user wants to offload a copy, they will first +.Fn ioat_acquire +the +.Ar bus_dmaengine_t +object for exclusive access to enqueue operations on that channel. +Optionally, the user can reserve space by using +.Fn ioat_acquire_reserve +instead. +If +.Fn ioat_acquire_reserve +succeeds, there is guaranteed to be room for +.Fa N +new operations in the internal ring buffer. +.Pp +Then, they will submit one or more operations using +.Fn ioat_blockfill , +.Fn ioat_copy , +.Fn ioat_copy_8k_aligned , +.Fn ioat_copy_crc , +.Fn ioat_crc , +or +.Fn ioat_null . +After queuing one or more individual DMA operations, they will +.Fn ioat_release +the +.Ar bus_dmaengine_t +to drop their exclusive access to the channel. +The routine they provided for the +.Fa callback_fn +argument will be invoked with the provided +.Fa callback_arg +when the operation is complete. +When they are finished with the +.Ar bus_dmaengine_t , +the user should +.Fn ioat_put_dmaengine . +.Pp +Users MUST NOT block between +.Fn ioat_acquire +and +.Fn ioat_release . +Users SHOULD NOT hold +.Ar bus_dmaengine_t +references for a very long time to enable fault recovery and kernel module +unload. +.Pp +For an example of usage, see +.Pa src/sys/dev/ioat/ioat_test.c . +.Sh FILES +.Bl -tag +.It Pa /dev/ioat_test +test device for +.Xr ioatcontrol 8 +.El +.Sh SEE ALSO +.Xr ioatcontrol 8 +.Sh HISTORY +The +.Nm +driver first appeared in +.Fx 11.0 . +.Sh AUTHORS +The +.Nm +driver was developed by +.An \&Jim Harris Aq Mt jimharris@FreeBSD.org , +.An \&Carl Delsey Aq Mt carl.r.delsey@intel.com , +and +.An \&Conrad Meyer Aq Mt cem@FreeBSD.org . +This manual page was written by +.An \&Conrad Meyer Aq Mt cem@FreeBSD.org . +.Sh CAVEATS +Copy operation takes bus addresses as parameters, not virtual addresses. +.Pp +Buffers for individual copy operations must be physically contiguous. +.Pp +Copies larger than max transfer size (1MB, but may vary by hardware) are not +supported. +Future versions will likely support this by breaking up the transfer into +smaller sizes. +.Sh BUGS +The +.Nm +driver only supports blockfill, copy, and null operations at this time. +The driver does not yet support advanced DMA modes, such as XOR, that some +I/OAT devices support.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201605250714.u4P7EqhX021703>