a9934668aa
camdd(8) utility.
CCBs may be queued to the driver via the new CAMIOQUEUE ioctl, and
completed CCBs may be retrieved via the CAMIOGET ioctl. User
processes can use poll(2) or kevent(2) to get notification when
I/O has completed.
While the existing CAMIOCOMMAND blocking ioctl interface only
supports user virtual data pointers in a CCB (generally only
one per CCB), the new CAMIOQUEUE ioctl supports user virtual and
physical address pointers, as well as user virtual and physical
scatter/gather lists. This allows user applications to have more
flexibility in their data handling operations.
Kernel memory for data transferred via the queued interface is
allocated from the zone allocator in MAXPHYS sized chunks, and user
data is copied in and out. This is likely faster than the
vmapbuf()/vunmapbuf() method used by the CAMIOCOMMAND ioctl in
configurations with many processors (there are more TLB shootdowns
caused by the mapping/unmapping operation) but may not be as fast
as running with unmapped I/O.
The new memory handling model for user requests also allows
applications to send CCBs with request sizes that are larger than
MAXPHYS. The pass(4) driver now limits queued requests to the I/O
size listed by the SIM driver in the maxio field in the Path
Inquiry (XPT_PATH_INQ) CCB.
There are some things things would be good to add:
1. Come up with a way to do unmapped I/O on multiple buffers.
Currently the unmapped I/O interface operates on a struct bio,
which includes only one address and length. It would be nice
to be able to send an unmapped scatter/gather list down to
busdma. This would allow eliminating the copy we currently do
for data.
2. Add an ioctl to list currently outstanding CCBs in the various
queues.
3. Add an ioctl to cancel a request, or use the XPT_ABORT CCB to do
that.
4. Test physical address support. Virtual pointers and scatter
gather lists have been tested, but I have not yet tested
physical addresses or scatter/gather lists.
5. Investigate multiple queue support. At the moment there is one
queue of commands per pass(4) device. If multiple processes
open the device, they will submit I/O into the same queue and
get events for the same completions. This is probably the right
model for most applications, but it is something that could be
changed later on.
Also, add a new utility, camdd(8) that uses the asynchronous pass(4)
driver interface.
This utility is intended to be a basic data transfer/copy utility,
a simple benchmark utility, and an example of how to use the
asynchronous pass(4) interface.
It can copy data to and from pass(4) devices using any target queue
depth, starting offset and blocksize for the input and ouptut devices.
It currently only supports SCSI devices, but could be easily extended
to support ATA devices.
It can also copy data to and from regular files, block devices, tape
devices, pipes, stdin, and stdout. It does not support queueing
multiple commands to any of those targets, since it uses the standard
read(2)/write(2)/writev(2)/readv(2) system calls.
The I/O is done by two threads, one for the reader and one for the
writer. The reader thread sends completed read requests to the
writer thread in strictly sequential order, even if they complete
out of order. That could be modified later on for random I/O patterns
or slightly out of order I/O.
camdd(8) uses kqueue(2)/kevent(2) to get I/O completion events from
the pass(4) driver and also to send request notifications internally.
For pass(4) devcies, camdd(8) uses a single buffer (CAM_DATA_VADDR)
per CAM CCB on the reading side, and a scatter/gather list
(CAM_DATA_SG) on the writing side. In addition to testing both
interfaces, this makes any potential reblocking of I/O easier. No
data is copied between the reader and the writer, but rather the
reader's buffers are split into multiple I/O requests or combined
into a single I/O request depending on the input and output blocksize.
For the file I/O path, camdd(8) also uses a single buffer (read(2),
write(2), pread(2) or pwrite(2)) on reads, and a scatter/gather list
(readv(2), writev(2), preadv(2), pwritev(2)) on writes.
Things that would be nice to do for camdd(8) eventually:
1. Add support for I/O pattern generation. Patterns like all
zeros, all ones, LBA-based patterns, random patterns, etc. Right
Now you can always use /dev/zero, /dev/random, etc.
2. Add support for a "sink" mode, so we do only reads with no
writes. Right now, you can use /dev/null.
3. Add support for automatic queue depth probing, so that we can
figure out the right queue depth on the input and output side
for maximum throughput. At the moment it defaults to 6.
4. Add support for SATA device passthrough I/O.
5. Add support for random LBAs and/or lengths on the input and
output sides.
6. Track average per-I/O latency and busy time. The busy time
and latency could also feed in to the automatic queue depth
determination.
sys/cam/scsi/scsi_pass.h:
Define two new ioctls, CAMIOQUEUE and CAMIOGET, that queue
and fetch asynchronous CAM CCBs respectively.
Although these ioctls do not have a declared argument, they
both take a union ccb pointer. If we declare a size here,
the ioctl code in sys/kern/sys_generic.c will malloc and free
a buffer for either the CCB or the CCB pointer (depending on
how it is declared). Since we have to keep a copy of the
CCB (which is fairly large) anyway, having the ioctl malloc
and free a CCB for each call is wasteful.
sys/cam/scsi/scsi_pass.c:
Add asynchronous CCB support.
Add two new ioctls, CAMIOQUEUE and CAMIOGET.
CAMIOQUEUE adds a CCB to the incoming queue. The CCB is
executed immediately (and moved to the active queue) if it
is an immediate CCB, but otherwise it will be executed
in passstart() when a CCB is available from the transport layer.
When CCBs are completed (because they are immediate or
passdone() if they are queued), they are put on the done
queue.
If we get the final close on the device before all pending
I/O is complete, all active I/O is moved to the abandoned
queue and we increment the peripheral reference count so
that the peripheral driver instance doesn't go away before
all pending I/O is done.
The new passcreatezone() function is called on the first
call to the CAMIOQUEUE ioctl on a given device to allocate
the UMA zones for I/O requests and S/G list buffers. This
may be good to move off to a taskqueue at some point.
The new passmemsetup() function allocates memory and
scatter/gather lists to hold the user's data, and copies
in any data that needs to be written. For virtual pointers
(CAM_DATA_VADDR), the kernel buffer is malloced from the
new pass(4) driver malloc bucket. For virtual
scatter/gather lists (CAM_DATA_SG), buffers are allocated
from a new per-pass(9) UMA zone in MAXPHYS-sized chunks.
Physical pointers are passed in unchanged. We have support
for up to 16 scatter/gather segments (for the user and
kernel S/G lists) in the default struct pass_io_req, so
requests with longer S/G lists require an extra kernel malloc.
The new passcopysglist() function copies a user scatter/gather
list to a kernel scatter/gather list. The number of elements
in each list may be different, but (obviously) the amount of data
stored has to be identical.
The new passmemdone() function copies data out for the
CAM_DATA_VADDR and CAM_DATA_SG cases.
The new passiocleanup() function restores data pointers in
user CCBs and frees memory.
Add new functions to support kqueue(2)/kevent(2):
passreadfilt() tells kevent whether or not the done
queue is empty.
passkqfilter() adds a knote to our list.
passreadfiltdetach() removes a knote from our list.
Add a new function, passpoll(), for poll(2)/select(2)
to use.
Add devstat(9) support for the queued CCB path.
sys/cam/ata/ata_da.c:
Add support for the BIO_VLIST bio type.
sys/cam/cam_ccb.h:
Add a new enumeration for the xflags field in the CCB header.
(This doesn't change the CCB header, just adds an enumeration to
use.)
sys/cam/cam_xpt.c:
Add a new function, xpt_setup_ccb_flags(), that allows specifying
CCB flags.
sys/cam/cam_xpt.h:
Add a prototype for xpt_setup_ccb_flags().
sys/cam/scsi/scsi_da.c:
Add support for BIO_VLIST.
sys/dev/md/md.c:
Add BIO_VLIST support to md(4).
sys/geom/geom_disk.c:
Add BIO_VLIST support to the GEOM disk class. Re-factor the I/O size
limiting code in g_disk_start() a bit.
sys/kern/subr_bus_dma.c:
Change _bus_dmamap_load_vlist() to take a starting offset and
length.
Add a new function, _bus_dmamap_load_pages(), that will load a list
of physical pages starting at an offset.
Update _bus_dmamap_load_bio() to allow loading BIO_VLIST bios.
Allow unmapped I/O to start at an offset.
sys/kern/subr_uio.c:
Add two new functions, physcopyin_vlist() and physcopyout_vlist().
sys/pc98/include/bus.h:
Guard kernel-only parts of the pc98 machine/bus.h header with
#ifdef _KERNEL.
This allows userland programs to include <machine/bus.h> to get the
definition of bus_addr_t and bus_size_t.
sys/sys/bio.h:
Add a new bio flag, BIO_VLIST.
sys/sys/uio.h:
Add prototypes for physcopyin_vlist() and physcopyout_vlist().
share/man/man4/pass.4:
Document the CAMIOQUEUE and CAMIOGET ioctls.
usr.sbin/Makefile:
Add camdd.
usr.sbin/camdd/Makefile:
Add a makefile for camdd(8).
usr.sbin/camdd/camdd.8:
Man page for camdd(8).
usr.sbin/camdd/camdd.c:
The new camdd(8) utility.
Sponsored by: Spectra Logic
MFC after: 1 week
160 lines
6.0 KiB
C
160 lines
6.0 KiB
C
/*-
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* Copyright (c) 1982, 1986, 1989, 1993
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* The Regents of the University of California. All rights reserved.
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* (c) UNIX System Laboratories, Inc.
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* All or some portions of this file are derived from material licensed
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* to the University of California by American Telephone and Telegraph
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* Co. or Unix System Laboratories, Inc. and are reproduced herein with
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* the permission of UNIX System Laboratories, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)buf.h 8.9 (Berkeley) 3/30/95
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* $FreeBSD$
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*/
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#ifndef _SYS_BIO_H_
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#define _SYS_BIO_H_
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#include <sys/queue.h>
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/* bio_cmd */
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#define BIO_READ 0x01 /* Read I/O data */
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#define BIO_WRITE 0x02 /* Write I/O data */
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#define BIO_DELETE 0x04 /* TRIM or free blocks, i.e. mark as unused */
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#define BIO_GETATTR 0x08 /* Get GEOM attributes of object */
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#define BIO_FLUSH 0x10 /* Commit outstanding I/O now */
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#define BIO_CMD0 0x20 /* Available for local hacks */
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#define BIO_CMD1 0x40 /* Available for local hacks */
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#define BIO_CMD2 0x80 /* Available for local hacks */
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/* bio_flags */
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#define BIO_ERROR 0x01 /* An error occurred processing this bio. */
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#define BIO_DONE 0x02 /* This bio is finished. */
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#define BIO_ONQUEUE 0x04 /* This bio is in a queue & not yet taken. */
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/*
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* This bio must be executed after all previous bios in the queue have been
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* executed, and before any successive bios can be executed.
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*/
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#define BIO_ORDERED 0x08
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#define BIO_UNMAPPED 0x10
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#define BIO_TRANSIENT_MAPPING 0x20
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#define BIO_VLIST 0x40
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#ifdef _KERNEL
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struct disk;
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struct bio;
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struct vm_map;
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/* Empty classifier tag, to prevent further classification. */
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#define BIO_NOTCLASSIFIED (void *)(~0UL)
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typedef void bio_task_t(void *);
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/*
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* The bio structure describes an I/O operation in the kernel.
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*/
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struct bio {
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uint8_t bio_cmd; /* I/O operation. */
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uint8_t bio_flags; /* General flags. */
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uint8_t bio_cflags; /* Private use by the consumer. */
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uint8_t bio_pflags; /* Private use by the provider. */
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struct cdev *bio_dev; /* Device to do I/O on. */
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struct disk *bio_disk; /* Valid below geom_disk.c only */
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off_t bio_offset; /* Offset into file. */
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long bio_bcount; /* Valid bytes in buffer. */
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caddr_t bio_data; /* Memory, superblocks, indirect etc. */
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struct vm_page **bio_ma; /* Or unmapped. */
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int bio_ma_offset; /* Offset in the first page of bio_ma. */
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int bio_ma_n; /* Number of pages in bio_ma. */
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int bio_error; /* Errno for BIO_ERROR. */
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long bio_resid; /* Remaining I/O in bytes. */
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void (*bio_done)(struct bio *);
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void *bio_driver1; /* Private use by the provider. */
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void *bio_driver2; /* Private use by the provider. */
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void *bio_caller1; /* Private use by the consumer. */
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void *bio_caller2; /* Private use by the consumer. */
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TAILQ_ENTRY(bio) bio_queue; /* Disksort queue. */
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const char *bio_attribute; /* Attribute for BIO_[GS]ETATTR */
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struct g_consumer *bio_from; /* GEOM linkage */
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struct g_provider *bio_to; /* GEOM linkage */
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off_t bio_length; /* Like bio_bcount */
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off_t bio_completed; /* Inverse of bio_resid */
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u_int bio_children; /* Number of spawned bios */
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u_int bio_inbed; /* Children safely home by now */
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struct bio *bio_parent; /* Pointer to parent */
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struct bintime bio_t0; /* Time request started */
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bio_task_t *bio_task; /* Task_queue handler */
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void *bio_task_arg; /* Argument to above */
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void *bio_classifier1; /* Classifier tag. */
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void *bio_classifier2; /* Classifier tag. */
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#ifdef DIAGNOSTIC
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void *_bio_caller1;
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void *_bio_caller2;
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uint8_t _bio_cflags;
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#endif
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/* XXX: these go away when bio chaining is introduced */
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daddr_t bio_pblkno; /* physical block number */
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};
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struct uio;
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struct devstat;
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struct bio_queue_head {
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TAILQ_HEAD(bio_queue, bio) queue;
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off_t last_offset;
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struct bio *insert_point;
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};
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extern struct vm_map *bio_transient_map;
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extern int bio_transient_maxcnt;
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void biodone(struct bio *bp);
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void biofinish(struct bio *bp, struct devstat *stat, int error);
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int biowait(struct bio *bp, const char *wchan);
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void bioq_disksort(struct bio_queue_head *ap, struct bio *bp);
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struct bio *bioq_first(struct bio_queue_head *head);
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struct bio *bioq_takefirst(struct bio_queue_head *head);
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void bioq_flush(struct bio_queue_head *head, struct devstat *stp, int error);
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void bioq_init(struct bio_queue_head *head);
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void bioq_insert_head(struct bio_queue_head *head, struct bio *bp);
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void bioq_insert_tail(struct bio_queue_head *head, struct bio *bp);
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void bioq_remove(struct bio_queue_head *head, struct bio *bp);
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void bio_taskqueue(struct bio *bp, bio_task_t *fund, void *arg);
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int physio(struct cdev *dev, struct uio *uio, int ioflag);
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#define physread physio
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#define physwrite physio
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#endif /* _KERNEL */
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#endif /* !_SYS_BIO_H_ */
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