Merge branch 'linus' into timers/core

Reason: Further posix_cpu_timer patches depend on mainline changes

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Thomas Gleixner
2010-05-10 11:59:37 +02:00
5707 changed files with 100983 additions and 21048 deletions
+1 -1
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@@ -160,7 +160,7 @@ Description:
match the driver to the device. For example:
# echo "046d c315" > /sys/bus/usb/drivers/foo/remove_id
What: /sys/bus/usb/device/.../avoid_reset
What: /sys/bus/usb/device/.../avoid_reset_quirk
Date: December 2009
Contact: Oliver Neukum <oliver@neukum.org>
Description:
+16 -33
View File
@@ -107,10 +107,6 @@ void (*dev_config) (struct ata_port *, struct ata_device *);
issue of SET FEATURES - XFER MODE, and prior to operation.
</para>
<para>
Called by ata_device_add() after ata_dev_identify() determines
a device is present.
</para>
<para>
This entry may be specified as NULL in ata_port_operations.
</para>
@@ -154,8 +150,8 @@ unsigned int (*mode_filter) (struct ata_port *, struct ata_device *, unsigned in
<sect2><title>Taskfile read/write</title>
<programlisting>
void (*tf_load) (struct ata_port *ap, struct ata_taskfile *tf);
void (*tf_read) (struct ata_port *ap, struct ata_taskfile *tf);
void (*sff_tf_load) (struct ata_port *ap, struct ata_taskfile *tf);
void (*sff_tf_read) (struct ata_port *ap, struct ata_taskfile *tf);
</programlisting>
<para>
@@ -164,36 +160,35 @@ void (*tf_read) (struct ata_port *ap, struct ata_taskfile *tf);
hardware registers / DMA buffers, to obtain the current set of
taskfile register values.
Most drivers for taskfile-based hardware (PIO or MMIO) use
ata_tf_load() and ata_tf_read() for these hooks.
ata_sff_tf_load() and ata_sff_tf_read() for these hooks.
</para>
</sect2>
<sect2><title>PIO data read/write</title>
<programlisting>
void (*data_xfer) (struct ata_device *, unsigned char *, unsigned int, int);
void (*sff_data_xfer) (struct ata_device *, unsigned char *, unsigned int, int);
</programlisting>
<para>
All bmdma-style drivers must implement this hook. This is the low-level
operation that actually copies the data bytes during a PIO data
transfer.
Typically the driver
will choose one of ata_pio_data_xfer_noirq(), ata_pio_data_xfer(), or
ata_mmio_data_xfer().
Typically the driver will choose one of ata_sff_data_xfer_noirq(),
ata_sff_data_xfer(), or ata_sff_data_xfer32().
</para>
</sect2>
<sect2><title>ATA command execute</title>
<programlisting>
void (*exec_command)(struct ata_port *ap, struct ata_taskfile *tf);
void (*sff_exec_command)(struct ata_port *ap, struct ata_taskfile *tf);
</programlisting>
<para>
causes an ATA command, previously loaded with
->tf_load(), to be initiated in hardware.
Most drivers for taskfile-based hardware use ata_exec_command()
Most drivers for taskfile-based hardware use ata_sff_exec_command()
for this hook.
</para>
@@ -218,8 +213,8 @@ command.
<sect2><title>Read specific ATA shadow registers</title>
<programlisting>
u8 (*check_status)(struct ata_port *ap);
u8 (*check_altstatus)(struct ata_port *ap);
u8 (*sff_check_status)(struct ata_port *ap);
u8 (*sff_check_altstatus)(struct ata_port *ap);
</programlisting>
<para>
@@ -227,20 +222,14 @@ u8 (*check_altstatus)(struct ata_port *ap);
hardware. On some hardware, reading the Status register has
the side effect of clearing the interrupt condition.
Most drivers for taskfile-based hardware use
ata_check_status() for this hook.
</para>
<para>
Note that because this is called from ata_device_add(), at
least a dummy function that clears device interrupts must be
provided for all drivers, even if the controller doesn't
actually have a taskfile status register.
ata_sff_check_status() for this hook.
</para>
</sect2>
<sect2><title>Select ATA device on bus</title>
<programlisting>
void (*dev_select)(struct ata_port *ap, unsigned int device);
void (*sff_dev_select)(struct ata_port *ap, unsigned int device);
</programlisting>
<para>
@@ -251,9 +240,7 @@ void (*dev_select)(struct ata_port *ap, unsigned int device);
</para>
<para>
Most drivers for taskfile-based hardware use
ata_std_dev_select() for this hook. Controllers which do not
support second drives on a port (such as SATA contollers) will
use ata_noop_dev_select().
ata_sff_dev_select() for this hook.
</para>
</sect2>
@@ -441,13 +428,13 @@ void (*irq_clear) (struct ata_port *);
to struct ata_host_set.
</para>
<para>
Most legacy IDE drivers use ata_interrupt() for the
Most legacy IDE drivers use ata_sff_interrupt() for the
irq_handler hook, which scans all ports in the host_set,
determines which queued command was active (if any), and calls
ata_host_intr(ap,qc).
ata_sff_host_intr(ap,qc).
</para>
<para>
Most legacy IDE drivers use ata_bmdma_irq_clear() for the
Most legacy IDE drivers use ata_sff_irq_clear() for the
irq_clear() hook, which simply clears the interrupt and error
flags in the DMA status register.
</para>
@@ -496,10 +483,6 @@ void (*host_stop) (struct ata_host_set *host_set);
data from port at this time.
</para>
<para>
Many drivers use ata_port_stop() as this hook, which frees the
PRD table.
</para>
<para>
->host_stop() is called after all ->port_stop() calls
have completed. The hook must finalize hardware shutdown, release DMA
and other resources, etc.
+13
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@@ -16,6 +16,15 @@
</address>
</affiliation>
</author>
<author>
<firstname>William</firstname>
<surname>Cohen</surname>
<affiliation>
<address>
<email>wcohen@redhat.com</email>
</address>
</affiliation>
</author>
</authorgroup>
<legalnotice>
@@ -91,4 +100,8 @@
!Iinclude/trace/events/signal.h
</chapter>
<chapter id="block">
<title>Block IO</title>
!Iinclude/trace/events/block.h
</chapter>
</book>
+1 -1
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@@ -234,7 +234,7 @@ process is as follows:
Linus, usually the patches that have already been included in the
-next kernel for a few weeks. The preferred way to submit big changes
is using git (the kernel's source management tool, more information
can be found at http://git.or.cz/) but plain patches are also just
can be found at http://git-scm.com/) but plain patches are also just
fine.
- After two weeks a -rc1 kernel is released it is now possible to push
only patches that do not include new features that could affect the
+21 -16
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@@ -34,7 +34,7 @@ NMI handler.
cpu = smp_processor_id();
++nmi_count(cpu);
if (!rcu_dereference(nmi_callback)(regs, cpu))
if (!rcu_dereference_sched(nmi_callback)(regs, cpu))
default_do_nmi(regs);
nmi_exit();
@@ -47,12 +47,13 @@ function pointer. If this handler returns zero, do_nmi() invokes the
default_do_nmi() function to handle a machine-specific NMI. Finally,
preemption is restored.
Strictly speaking, rcu_dereference() is not needed, since this code runs
only on i386, which does not need rcu_dereference() anyway. However,
it is a good documentation aid, particularly for anyone attempting to
do something similar on Alpha.
In theory, rcu_dereference_sched() is not needed, since this code runs
only on i386, which in theory does not need rcu_dereference_sched()
anyway. However, in practice it is a good documentation aid, particularly
for anyone attempting to do something similar on Alpha or on systems
with aggressive optimizing compilers.
Quick Quiz: Why might the rcu_dereference() be necessary on Alpha,
Quick Quiz: Why might the rcu_dereference_sched() be necessary on Alpha,
given that the code referenced by the pointer is read-only?
@@ -99,17 +100,21 @@ invoke irq_enter() and irq_exit() on NMI entry and exit, respectively.
Answer to Quick Quiz
Why might the rcu_dereference() be necessary on Alpha, given
Why might the rcu_dereference_sched() be necessary on Alpha, given
that the code referenced by the pointer is read-only?
Answer: The caller to set_nmi_callback() might well have
initialized some data that is to be used by the
new NMI handler. In this case, the rcu_dereference()
would be needed, because otherwise a CPU that received
an NMI just after the new handler was set might see
the pointer to the new NMI handler, but the old
pre-initialized version of the handler's data.
initialized some data that is to be used by the new NMI
handler. In this case, the rcu_dereference_sched() would
be needed, because otherwise a CPU that received an NMI
just after the new handler was set might see the pointer
to the new NMI handler, but the old pre-initialized
version of the handler's data.
More important, the rcu_dereference() makes it clear
to someone reading the code that the pointer is being
protected by RCU.
This same sad story can happen on other CPUs when using
a compiler with aggressive pointer-value speculation
optimizations.
More important, the rcu_dereference_sched() makes it
clear to someone reading the code that the pointer is
being protected by RCU-sched.
+4 -3
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@@ -260,7 +260,8 @@ over a rather long period of time, but improvements are always welcome!
The reason that it is permissible to use RCU list-traversal
primitives when the update-side lock is held is that doing so
can be quite helpful in reducing code bloat when common code is
shared between readers and updaters.
shared between readers and updaters. Additional primitives
are provided for this case, as discussed in lockdep.txt.
10. Conversely, if you are in an RCU read-side critical section,
and you don't hold the appropriate update-side lock, you -must-
@@ -344,8 +345,8 @@ over a rather long period of time, but improvements are always welcome!
requiring SRCU's read-side deadlock immunity or low read-side
realtime latency.
Note that, rcu_assign_pointer() and rcu_dereference() relate to
SRCU just as they do to other forms of RCU.
Note that, rcu_assign_pointer() relates to SRCU just as they do
to other forms of RCU.
15. The whole point of call_rcu(), synchronize_rcu(), and friends
is to wait until all pre-existing readers have finished before
+26 -2
View File
@@ -32,9 +32,20 @@ checking of rcu_dereference() primitives:
srcu_dereference(p, sp):
Check for SRCU read-side critical section.
rcu_dereference_check(p, c):
Use explicit check expression "c".
Use explicit check expression "c". This is useful in
code that is invoked by both readers and updaters.
rcu_dereference_raw(p)
Don't check. (Use sparingly, if at all.)
rcu_dereference_protected(p, c):
Use explicit check expression "c", and omit all barriers
and compiler constraints. This is useful when the data
structure cannot change, for example, in code that is
invoked only by updaters.
rcu_access_pointer(p):
Return the value of the pointer and omit all barriers,
but retain the compiler constraints that prevent duplicating
or coalescsing. This is useful when when testing the
value of the pointer itself, for example, against NULL.
The rcu_dereference_check() check expression can be any boolean
expression, but would normally include one of the rcu_read_lock_held()
@@ -59,7 +70,20 @@ In case (1), the pointer is picked up in an RCU-safe manner for vanilla
RCU read-side critical sections, in case (2) the ->file_lock prevents
any change from taking place, and finally, in case (3) the current task
is the only task accessing the file_struct, again preventing any change
from taking place.
from taking place. If the above statement was invoked only from updater
code, it could instead be written as follows:
file = rcu_dereference_protected(fdt->fd[fd],
lockdep_is_held(&files->file_lock) ||
atomic_read(&files->count) == 1);
This would verify cases #2 and #3 above, and furthermore lockdep would
complain if this was used in an RCU read-side critical section unless one
of these two cases held. Because rcu_dereference_protected() omits all
barriers and compiler constraints, it generates better code than do the
other flavors of rcu_dereference(). On the other hand, it is illegal
to use rcu_dereference_protected() if either the RCU-protected pointer
or the RCU-protected data that it points to can change concurrently.
There are currently only "universal" versions of the rcu_assign_pointer()
and RCU list-/tree-traversal primitives, which do not (yet) check for
+6
View File
@@ -840,6 +840,12 @@ SRCU: Initialization/cleanup
init_srcu_struct
cleanup_srcu_struct
All: lockdep-checked RCU-protected pointer access
rcu_dereference_check
rcu_dereference_protected
rcu_access_pointer
See the comment headers in the source code (or the docbook generated
from them) for more information.
+2 -2
View File
@@ -1162,8 +1162,8 @@ where a driver received a request ala this before:
As mentioned, there is no virtual mapping of a bio. For DMA, this is
not a problem as the driver probably never will need a virtual mapping.
Instead it needs a bus mapping (pci_map_page for a single segment or
use blk_rq_map_sg for scatter gather) to be able to ship it to the driver. For
Instead it needs a bus mapping (dma_map_page for a single segment or
use dma_map_sg for scatter gather) to be able to ship it to the driver. For
PIO drivers (or drivers that need to revert to PIO transfer once in a
while (IDE for example)), where the CPU is doing the actual data
transfer a virtual mapping is needed. If the driver supports highmem I/O,
+1 -2
View File
@@ -235,8 +235,7 @@ containing the following files describing that cgroup:
- cgroup.procs: list of tgids in the cgroup. This list is not
guaranteed to be sorted or free of duplicate tgids, and userspace
should sort/uniquify the list if this property is required.
Writing a tgid into this file moves all threads with that tgid into
this cgroup.
This is a read-only file, for now.
- notify_on_release flag: run the release agent on exit?
- release_agent: the path to use for release notifications (this file
exists in the top cgroup only)
+1 -1
View File
@@ -340,7 +340,7 @@ Note:
5.3 swappiness
Similar to /proc/sys/vm/swappiness, but affecting a hierarchy of groups only.
Following cgroups' swapiness can't be changed.
Following cgroups' swappiness can't be changed.
- root cgroup (uses /proc/sys/vm/swappiness).
- a cgroup which uses hierarchy and it has child cgroup.
- a cgroup which uses hierarchy and not the root of hierarchy.
+234
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@@ -0,0 +1,234 @@
================
CIRCULAR BUFFERS
================
By: David Howells <dhowells@redhat.com>
Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Linux provides a number of features that can be used to implement circular
buffering. There are two sets of such features:
(1) Convenience functions for determining information about power-of-2 sized
buffers.
(2) Memory barriers for when the producer and the consumer of objects in the
buffer don't want to share a lock.
To use these facilities, as discussed below, there needs to be just one
producer and just one consumer. It is possible to handle multiple producers by
serialising them, and to handle multiple consumers by serialising them.
Contents:
(*) What is a circular buffer?
(*) Measuring power-of-2 buffers.
(*) Using memory barriers with circular buffers.
- The producer.
- The consumer.
==========================
WHAT IS A CIRCULAR BUFFER?
==========================
First of all, what is a circular buffer? A circular buffer is a buffer of
fixed, finite size into which there are two indices:
(1) A 'head' index - the point at which the producer inserts items into the
buffer.
(2) A 'tail' index - the point at which the consumer finds the next item in
the buffer.
Typically when the tail pointer is equal to the head pointer, the buffer is
empty; and the buffer is full when the head pointer is one less than the tail
pointer.
The head index is incremented when items are added, and the tail index when
items are removed. The tail index should never jump the head index, and both
indices should be wrapped to 0 when they reach the end of the buffer, thus
allowing an infinite amount of data to flow through the buffer.
Typically, items will all be of the same unit size, but this isn't strictly
required to use the techniques below. The indices can be increased by more
than 1 if multiple items or variable-sized items are to be included in the
buffer, provided that neither index overtakes the other. The implementer must
be careful, however, as a region more than one unit in size may wrap the end of
the buffer and be broken into two segments.
============================
MEASURING POWER-OF-2 BUFFERS
============================
Calculation of the occupancy or the remaining capacity of an arbitrarily sized
circular buffer would normally be a slow operation, requiring the use of a
modulus (divide) instruction. However, if the buffer is of a power-of-2 size,
then a much quicker bitwise-AND instruction can be used instead.
Linux provides a set of macros for handling power-of-2 circular buffers. These
can be made use of by:
#include <linux/circ_buf.h>
The macros are:
(*) Measure the remaining capacity of a buffer:
CIRC_SPACE(head_index, tail_index, buffer_size);
This returns the amount of space left in the buffer[1] into which items
can be inserted.
(*) Measure the maximum consecutive immediate space in a buffer:
CIRC_SPACE_TO_END(head_index, tail_index, buffer_size);
This returns the amount of consecutive space left in the buffer[1] into
which items can be immediately inserted without having to wrap back to the
beginning of the buffer.
(*) Measure the occupancy of a buffer:
CIRC_CNT(head_index, tail_index, buffer_size);
This returns the number of items currently occupying a buffer[2].
(*) Measure the non-wrapping occupancy of a buffer:
CIRC_CNT_TO_END(head_index, tail_index, buffer_size);
This returns the number of consecutive items[2] that can be extracted from
the buffer without having to wrap back to the beginning of the buffer.
Each of these macros will nominally return a value between 0 and buffer_size-1,
however:
[1] CIRC_SPACE*() are intended to be used in the producer. To the producer
they will return a lower bound as the producer controls the head index,
but the consumer may still be depleting the buffer on another CPU and
moving the tail index.
To the consumer it will show an upper bound as the producer may be busy
depleting the space.
[2] CIRC_CNT*() are intended to be used in the consumer. To the consumer they
will return a lower bound as the consumer controls the tail index, but the
producer may still be filling the buffer on another CPU and moving the
head index.
To the producer it will show an upper bound as the consumer may be busy
emptying the buffer.
[3] To a third party, the order in which the writes to the indices by the
producer and consumer become visible cannot be guaranteed as they are
independent and may be made on different CPUs - so the result in such a
situation will merely be a guess, and may even be negative.
===========================================
USING MEMORY BARRIERS WITH CIRCULAR BUFFERS
===========================================
By using memory barriers in conjunction with circular buffers, you can avoid
the need to:
(1) use a single lock to govern access to both ends of the buffer, thus
allowing the buffer to be filled and emptied at the same time; and
(2) use atomic counter operations.
There are two sides to this: the producer that fills the buffer, and the
consumer that empties it. Only one thing should be filling a buffer at any one
time, and only one thing should be emptying a buffer at any one time, but the
two sides can operate simultaneously.
THE PRODUCER
------------
The producer will look something like this:
spin_lock(&producer_lock);
unsigned long head = buffer->head;
unsigned long tail = ACCESS_ONCE(buffer->tail);
if (CIRC_SPACE(head, tail, buffer->size) >= 1) {
/* insert one item into the buffer */
struct item *item = buffer[head];
produce_item(item);
smp_wmb(); /* commit the item before incrementing the head */
buffer->head = (head + 1) & (buffer->size - 1);
/* wake_up() will make sure that the head is committed before
* waking anyone up */
wake_up(consumer);
}
spin_unlock(&producer_lock);
This will instruct the CPU that the contents of the new item must be written
before the head index makes it available to the consumer and then instructs the
CPU that the revised head index must be written before the consumer is woken.
Note that wake_up() doesn't have to be the exact mechanism used, but whatever
is used must guarantee a (write) memory barrier between the update of the head
index and the change of state of the consumer, if a change of state occurs.
THE CONSUMER
------------
The consumer will look something like this:
spin_lock(&consumer_lock);
unsigned long head = ACCESS_ONCE(buffer->head);
unsigned long tail = buffer->tail;
if (CIRC_CNT(head, tail, buffer->size) >= 1) {
/* read index before reading contents at that index */
smp_read_barrier_depends();
/* extract one item from the buffer */
struct item *item = buffer[tail];
consume_item(item);
smp_mb(); /* finish reading descriptor before incrementing tail */
buffer->tail = (tail + 1) & (buffer->size - 1);
}
spin_unlock(&consumer_lock);
This will instruct the CPU to make sure the index is up to date before reading
the new item, and then it shall make sure the CPU has finished reading the item
before it writes the new tail pointer, which will erase the item.
Note the use of ACCESS_ONCE() in both algorithms to read the opposition index.
This prevents the compiler from discarding and reloading its cached value -
which some compilers will do across smp_read_barrier_depends(). This isn't
strictly needed if you can be sure that the opposition index will _only_ be
used the once.
===============
FURTHER READING
===============
See also Documentation/memory-barriers.txt for a description of Linux's memory
barrier facilities.
+1
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@@ -25,6 +25,7 @@
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/timer.h>
#include <linux/connector.h>
@@ -1,9 +1,9 @@
What is imacfb?
What is efifb?
===============
This is a generic EFI platform driver for Intel based Apple computers.
Imacfb is only for EFI booted Intel Macs.
efifb is only for EFI booted Intel Macs.
Supported Hardware
==================
@@ -16,16 +16,16 @@ MacMini
How to use it?
==============
Imacfb does not have any kind of autodetection of your machine.
efifb does not have any kind of autodetection of your machine.
You have to add the following kernel parameters in your elilo.conf:
Macbook :
video=imacfb:macbook
video=efifb:macbook
MacMini :
video=imacfb:mini
video=efifb:mini
Macbook Pro 15", iMac 17" :
video=imacfb:i17
video=efifb:i17
Macbook Pro 17", iMac 20" :
video=imacfb:i20
video=efifb:i20
--
Edgar Hucek <gimli@dark-green.com>
@@ -599,3 +599,26 @@ Why: Useful in 2003, implementation is a hack.
Generally invoked by accident today.
Seen as doing more harm than good.
Who: Len Brown <len.brown@intel.com>
----------------------------
What: video4linux /dev/vtx teletext API support
When: 2.6.35
Files: drivers/media/video/saa5246a.c drivers/media/video/saa5249.c
include/linux/videotext.h
Why: The vtx device nodes have been superseded by vbi device nodes
for many years. No applications exist that use the vtx support.
Of the two i2c drivers that actually support this API the saa5249
has been impossible to use for a year now and no known hardware
that supports this device exists. The saa5246a is theoretically
supported by the old mxb boards, but it never actually worked.
In summary: there is no hardware that can use this API and there
are no applications actually implementing this API.
The vtx support still reserves minors 192-223 and we would really
like to reuse those for upcoming new functionality. In the unlikely
event that new hardware appears that wants to use the functionality
provided by the vtx API, then that functionality should be build
around the sliced VBI API instead.
Who: Hans Verkuil <hverkuil@xs4all.nl>
+2
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@@ -16,6 +16,8 @@ befs.txt
- information about the BeOS filesystem for Linux.
bfs.txt
- info for the SCO UnixWare Boot Filesystem (BFS).
ceph.txt
- info for the Ceph Distributed File System
cifs.txt
- description of the CIFS filesystem.
coda.txt
+16 -2
View File
@@ -37,6 +37,15 @@ For Plan 9 From User Space applications (http://swtch.com/plan9)
mount -t 9p `namespace`/acme /mnt/9 -o trans=unix,uname=$USER
For server running on QEMU host with virtio transport:
mount -t 9p -o trans=virtio <mount_tag> /mnt/9
where mount_tag is the tag associated by the server to each of the exported
mount points. Each 9P export is seen by the client as a virtio device with an
associated "mount_tag" property. Available mount tags can be
seen by reading /sys/bus/virtio/drivers/9pnet_virtio/virtio<n>/mount_tag files.
OPTIONS
=======
@@ -47,7 +56,7 @@ OPTIONS
fd - used passed file descriptors for connection
(see rfdno and wfdno)
virtio - connect to the next virtio channel available
(from lguest or KVM with trans_virtio module)
(from QEMU with trans_virtio module)
rdma - connect to a specified RDMA channel
uname=name user name to attempt mount as on the remote server. The
@@ -85,7 +94,12 @@ OPTIONS
port=n port to connect to on the remote server
noextend force legacy mode (no 9p2000.u semantics)
noextend force legacy mode (no 9p2000.u or 9p2000.L semantics)
version=name Select 9P protocol version. Valid options are:
9p2000 - Legacy mode (same as noextend)
9p2000.u - Use 9P2000.u protocol
9p2000.L - Use 9P2000.L protocol
dfltuid attempt to mount as a particular uid
+140
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@@ -0,0 +1,140 @@
Ceph Distributed File System
============================
Ceph is a distributed network file system designed to provide good
performance, reliability, and scalability.
Basic features include:
* POSIX semantics
* Seamless scaling from 1 to many thousands of nodes
* High availability and reliability. No single point of failure.
* N-way replication of data across storage nodes
* Fast recovery from node failures
* Automatic rebalancing of data on node addition/removal
* Easy deployment: most FS components are userspace daemons
Also,
* Flexible snapshots (on any directory)
* Recursive accounting (nested files, directories, bytes)
In contrast to cluster filesystems like GFS, OCFS2, and GPFS that rely
on symmetric access by all clients to shared block devices, Ceph
separates data and metadata management into independent server
clusters, similar to Lustre. Unlike Lustre, however, metadata and
storage nodes run entirely as user space daemons. Storage nodes
utilize btrfs to store data objects, leveraging its advanced features
(checksumming, metadata replication, etc.). File data is striped
across storage nodes in large chunks to distribute workload and
facilitate high throughputs. When storage nodes fail, data is
re-replicated in a distributed fashion by the storage nodes themselves
(with some minimal coordination from a cluster monitor), making the
system extremely efficient and scalable.
Metadata servers effectively form a large, consistent, distributed
in-memory cache above the file namespace that is extremely scalable,
dynamically redistributes metadata in response to workload changes,
and can tolerate arbitrary (well, non-Byzantine) node failures. The
metadata server takes a somewhat unconventional approach to metadata
storage to significantly improve performance for common workloads. In
particular, inodes with only a single link are embedded in
directories, allowing entire directories of dentries and inodes to be
loaded into its cache with a single I/O operation. The contents of
extremely large directories can be fragmented and managed by
independent metadata servers, allowing scalable concurrent access.
The system offers automatic data rebalancing/migration when scaling
from a small cluster of just a few nodes to many hundreds, without
requiring an administrator carve the data set into static volumes or
go through the tedious process of migrating data between servers.
When the file system approaches full, new nodes can be easily added
and things will "just work."
Ceph includes flexible snapshot mechanism that allows a user to create
a snapshot on any subdirectory (and its nested contents) in the
system. Snapshot creation and deletion are as simple as 'mkdir
.snap/foo' and 'rmdir .snap/foo'.
Ceph also provides some recursive accounting on directories for nested
files and bytes. That is, a 'getfattr -d foo' on any directory in the
system will reveal the total number of nested regular files and
subdirectories, and a summation of all nested file sizes. This makes
the identification of large disk space consumers relatively quick, as
no 'du' or similar recursive scan of the file system is required.
Mount Syntax
============
The basic mount syntax is:
# mount -t ceph monip[:port][,monip2[:port]...]:/[subdir] mnt
You only need to specify a single monitor, as the client will get the
full list when it connects. (However, if the monitor you specify
happens to be down, the mount won't succeed.) The port can be left
off if the monitor is using the default. So if the monitor is at
1.2.3.4,
# mount -t ceph 1.2.3.4:/ /mnt/ceph
is sufficient. If /sbin/mount.ceph is installed, a hostname can be
used instead of an IP address.
Mount Options
=============
ip=A.B.C.D[:N]
Specify the IP and/or port the client should bind to locally.
There is normally not much reason to do this. If the IP is not
specified, the client's IP address is determined by looking at the
address it's connection to the monitor originates from.
wsize=X
Specify the maximum write size in bytes. By default there is no
maximum. Ceph will normally size writes based on the file stripe
size.
rsize=X
Specify the maximum readahead.
mount_timeout=X
Specify the timeout value for mount (in seconds), in the case
of a non-responsive Ceph file system. The default is 30
seconds.
rbytes
When stat() is called on a directory, set st_size to 'rbytes',
the summation of file sizes over all files nested beneath that
directory. This is the default.
norbytes
When stat() is called on a directory, set st_size to the
number of entries in that directory.
nocrc
Disable CRC32C calculation for data writes. If set, the storage node
must rely on TCP's error correction to detect data corruption
in the data payload.
noasyncreaddir
Disable client's use its local cache to satisfy readdir
requests. (This does not change correctness; the client uses
cached metadata only when a lease or capability ensures it is
valid.)
More Information
================
For more information on Ceph, see the home page at
http://ceph.newdream.net/
The Linux kernel client source tree is available at
git://ceph.newdream.net/git/ceph-client.git
git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client.git
and the source for the full system is at
git://ceph.newdream.net/git/ceph.git
+5 -1
View File
@@ -82,11 +82,13 @@ tmpfs has a mount option to set the NUMA memory allocation policy for
all files in that instance (if CONFIG_NUMA is enabled) - which can be
adjusted on the fly via 'mount -o remount ...'
mpol=default prefers to allocate memory from the local node
mpol=default use the process allocation policy
(see set_mempolicy(2))
mpol=prefer:Node prefers to allocate memory from the given Node
mpol=bind:NodeList allocates memory only from nodes in NodeList
mpol=interleave prefers to allocate from each node in turn
mpol=interleave:NodeList allocates from each node of NodeList in turn
mpol=local prefers to allocate memory from the local node
NodeList format is a comma-separated list of decimal numbers and ranges,
a range being two hyphen-separated decimal numbers, the smallest and
@@ -134,3 +136,5 @@ Author:
Christoph Rohland <cr@sap.com>, 1.12.01
Updated:
Hugh Dickins, 4 June 2007
Updated:
KOSAKI Motohiro, 16 Mar 2010

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