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freebsd-nq/share/man/man9/jumbo.9

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At long last, commit the zero copy sockets code. MAKEDEV: Add MAKEDEV glue for the ti(4) device nodes. ti.4: Update the ti(4) man page to include information on the TI_JUMBO_HDRSPLIT and TI_PRIVATE_JUMBOS kernel options, and also include information about the new character device interface and the associated ioctls. man9/Makefile: Add jumbo.9 and zero_copy.9 man pages and associated links. jumbo.9: New man page describing the jumbo buffer allocator interface and operation. zero_copy.9: New man page describing the general characteristics of the zero copy send and receive code, and what an application author should do to take advantage of the zero copy functionality. NOTES: Add entries for ZERO_COPY_SOCKETS, TI_PRIVATE_JUMBOS, TI_JUMBO_HDRSPLIT, MSIZE, and MCLSHIFT. conf/files: Add uipc_jumbo.c and uipc_cow.c. conf/options: Add the 5 options mentioned above. kern_subr.c: Receive side zero copy implementation. This takes "disposable" pages attached to an mbuf, gives them to a user process, and then recycles the user's page. This is only active when ZERO_COPY_SOCKETS is turned on and the kern.ipc.zero_copy.receive sysctl variable is set to 1. uipc_cow.c: Send side zero copy functions. Takes a page written by the user and maps it copy on write and assigns it kernel virtual address space. Removes copy on write mapping once the buffer has been freed by the network stack. uipc_jumbo.c: Jumbo disposable page allocator code. This allocates (optionally) disposable pages for network drivers that want to give the user the option of doing zero copy receive. uipc_socket.c: Add kern.ipc.zero_copy.{send,receive} sysctls that are enabled if ZERO_COPY_SOCKETS is turned on. Add zero copy send support to sosend() -- pages get mapped into the kernel instead of getting copied if they meet size and alignment restrictions. uipc_syscalls.c:Un-staticize some of the sf* functions so that they can be used elsewhere. (uipc_cow.c) if_media.c: In the SIOCGIFMEDIA ioctl in ifmedia_ioctl(), avoid calling malloc() with M_WAITOK. Return an error if the M_NOWAIT malloc fails. The ti(4) driver and the wi(4) driver, at least, call this with a mutex held. This causes witness warnings for 'ifconfig -a' with a wi(4) or ti(4) board in the system. (I've only verified for ti(4)). ip_output.c: Fragment large datagrams so that each segment contains a multiple of PAGE_SIZE amount of data plus headers. This allows the receiver to potentially do page flipping on receives. if_ti.c: Add zero copy receive support to the ti(4) driver. If TI_PRIVATE_JUMBOS is not defined, it now uses the jumbo(9) buffer allocator for jumbo receive buffers. Add a new character device interface for the ti(4) driver for the new debugging interface. This allows (a patched version of) gdb to talk to the Tigon board and debug the firmware. There are also a few additional debugging ioctls available through this interface. Add header splitting support to the ti(4) driver. Tweak some of the default interrupt coalescing parameters to more useful defaults. Add hooks for supporting transmit flow control, but leave it turned off with a comment describing why it is turned off. if_tireg.h: Change the firmware rev to 12.4.11, since we're really at 12.4.11 plus fixes from 12.4.13. Add defines needed for debugging. Remove the ti_stats structure, it is now defined in sys/tiio.h. ti_fw.h: 12.4.11 firmware. ti_fw2.h: 12.4.11 firmware, plus selected fixes from 12.4.13, and my header splitting patches. Revision 12.4.13 doesn't handle 10/100 negotiation properly. (This firmware is the same as what was in the tree previously, with the addition of header splitting support.) sys/jumbo.h: Jumbo buffer allocator interface. sys/mbuf.h: Add a new external mbuf type, EXT_DISPOSABLE, to indicate that the payload buffer can be thrown away / flipped to a userland process. socketvar.h: Add prototype for socow_setup. tiio.h: ioctl interface to the character portion of the ti(4) driver, plus associated structure/type definitions. uio.h: Change prototype for uiomoveco() so that we'll know whether the source page is disposable. ufs_readwrite.c:Update for new prototype of uiomoveco(). vm_fault.c: In vm_fault(), check to see whether we need to do a page based copy on write fault. vm_object.c: Add a new function, vm_object_allocate_wait(). This does the same thing that vm_object allocate does, except that it gives the caller the opportunity to specify whether it should wait on the uma_zalloc() of the object structre. This allows vm objects to be allocated while holding a mutex. (Without generating WITNESS warnings.) vm_object_allocate() is implemented as a call to vm_object_allocate_wait() with the malloc flag set to M_WAITOK. vm_object.h: Add prototype for vm_object_allocate_wait(). vm_page.c: Add page-based copy on write setup, clear and fault routines. vm_page.h: Add page based COW function prototypes and variable in the vm_page structure. Many thanks to Drew Gallatin, who wrote the zero copy send and receive code, and to all the other folks who have tested and reviewed this code over the years.
2002-06-26 03:37:47 +00:00
.\"
.\" Copyright (c) 2002 Kenneth D. Merry.
.\" 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,
.\" without modification, immediately at the beginning of the file.
.\" 2. The name of the author may not be used to endorse or promote products
.\" derived from this software without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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 June 23, 2002
.Dt JUMBO 9
.Os
.Sh NAME
.Nm jumbo ,
.Nm jumbo_vm_init ,
.Nm jumbo_pg_alloc ,
.Nm jumbo_pg_free ,
.Nm jumbo_freem ,
.Nm jumbo_pg_steal ,
.Nm jumbo_phys_to_kva
.Nd kernel interface for allocating and freeing page-sized disposable buffers
.Sh SYNOPSIS
.In sys/jumbo.h
.Ft int
.Fo jumbo_vm_init
.Fa "void"
.Fc
.Ft vm_page_t
.Fo jumbo_pg_alloc
.Fa "void"
.Fc
.Ft void
.Fo jumbo_pg_free
.Fa "vm_offset_t addr"
.Fc
.Ft void
.Fo jumbo_freem
.Fa "caddr_t addr"
.Fa "void *args"
.Fc
.Ft void
.Fo jumbo_pg_steal
.Fa "vm_page_t pg"
.Fc
.Ft caddr_t
.Fo jumbo_phys_to_kva
.Fa "vm_offset_t pa"
.Fc
.Sh DESCRIPTION
The
.Nm
buffer facility is designed for allocating disposable page-sized
buffers. Buffers allocated via this facility can either be returned or
not. This facility is primarily intended for use with network adapters
that have MTUs of a page or greater size. The buffers will normally be
disposed of by the
.Xr zero_copy 9
receive code.
.Pp
.Fn jumbo_vm_init
initializes the pool of KVA the
.Nm
code needs to operate and does some
other initialization to prepare the subsystem for operation. This routine
only needs to be called once. Calling it multiple times will have no
effect. It is recommended that this initialization routine be called in a
device driver attach routine, so that resources are not allocated if the
.Nm
subsystem won't end up being used.
.Fn jumbo_vm_init
returns 1 upon successful completion, and 0 upon failure.
.Pp
.Fn jumbo_pg_alloc
allocates a physical page and assigns a piece of KVA from the
.Nm
KVA pool. It returns the allocated page if successful, and NULL in the case of
failure.
.Pp
.Fn jumbo_pg_free
frees a page allocated by
.Fn jumbo_pg_alloc .
It takes the address of the memory in question as an argument. This
routine will normally be used in cases where the allocated
.Nm jumbo
page cannot be used for some reason. The normal free path is via
.Fn jumbo_freem .
.Pp
.Fn jumbo_freem
is the routine that should be given as the external free routine when an
external mbuf is allocated using pages from the
.Nm
allocator. It takes the virtual address of the page in question, and
ignores the second argument.
.Pp
.Fn jumbo_pg_steal
"steals" a page and recycles its KVA space.
.Pp
.Fn jumbo_phys_to_kva
translates the physical address of a
.Nm
allocated page to the proper kernel virtual address.
.Sh SEE ALSO
.Xr ti 4 ,
.Xr zero_copy 9
.Sh HISTORY
The
.Nm
allocator is primarily based on a page allocator system originally written
by
.An Andrew Gallatin Aq gallatin@FreeBSD.org
as part of a set of zero copy patches for the
.Xr ti 4
driver. The allocator was taken out of the
.Xr ti 4
driver, cleaned up and ported to the new mutex interface by
.An Kenneth Merry Aq ken@FreeBSD.org .
.Pp
The
.Nm
allocator first appeared in
.Fx 5.0 ,
and has existed in patch form since at least 1999.
.Sh AUTHORS
.An Andrew Gallatin Aq gallatin@FreeBSD.org
and
.An Kenneth Merry Aq ken@FreeBSD.org .
.Sh BUGS
There is currently a static number of KVA pages allocated by the
.Nm
allocator, with no real provision for increasing the number of pages
allocated should demand exceed supply.
.Pp
The
.Fn jumbo_pg_steal
function isn't currently used anywhere.
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