Add support for LED triggers to the LED subsystem. "Triggers" are events
which change the state of an LED. Two kinds of trigger are available, simple
ones which can be added to exising code with minimum disruption and complex
ones for implementing new or more complex functionality.
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add the foundations of a new LEDs subsystem. This patch adds a class which
presents LED devices within sysfs and allows their brightness to be
controlled.
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add TIOCL_GETKMSGREDIRECT needed by the userland suspend tool to get the
current value of kmsg_redirect from the kernel so that it can save it and
restore it after resume.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@suse.cz>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Remove the recently-added LINUX_FADV_ASYNC_WRITE and LINUX_FADV_WRITE_WAIT
fadvise() additions, do it in a new sys_sync_file_range() syscall instead.
Reasons:
- It's more flexible. Things which would require two or three syscalls with
fadvise() can be done in a single syscall.
- Using fadvise() in this manner is something not covered by POSIX.
The patch wires up the syscall for x86.
The sycall is implemented in the new fs/sync.c. The intention is that we can
move sys_fsync(), sys_fdatasync() and perhaps sys_sync() into there later.
Documentation for the syscall is in fs/sync.c.
A test app (sync_file_range.c) is in
http://www.zip.com.au/~akpm/linux/patches/stuff/ext3-tools.tar.gz.
The available-to-GPL-modules do_sync_file_range() is for knfsd: "A COMMIT can
say NFS_DATA_SYNC or NFS_FILE_SYNC. I can skip the ->fsync call for
NFS_DATA_SYNC which is hopefully the more common."
Note: the `async' writeout mode SYNC_FILE_RANGE_WRITE will turn synchronous if
the queue is congested. This is trivial to fix: add a new flag bit, set
wbc->nonblocking. But I'm not sure that we want to expose implementation
details down to that level.
Note: it's notable that we can sync an fd which wasn't opened for writing.
Same with fsync() and fdatasync()).
Note: the code takes some care to handle attempts to sync file contents
outside the 16TB offset on 32-bit machines. It makes such attempts appear to
succeed, for best 32-bit/64-bit compatibility. Perhaps it should make such
requests fail...
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Ulrich Drepper <drepper@redhat.com>
Cc: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Matt Domsch noticed a startup race with the IPMI kernel thread, it was
possible (though extraordinarly unlikely) that a message could come in
before the upper layer was ready to handle it. This patch splits the
startup processing of an IPMI interface into two parts, one to get ready
and one to actually start the processes to receive messages from the
interface.
[akpm@osdl.org: cleanups]
Signed-off-by: Corey Minyard <minyard@acm.org>
Cc: Matt Domsch <Matt_Domsch@dell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Make baby-simple the code for /proc/devices. Based on the proven design
for /proc/interrupts.
This also fixes the early-termination regression 2.6.16 introduced, as
demonstrated by:
# dd if=/proc/devices bs=1
Character devices:
1 mem
27+0 records in
27+0 records out
This should also work (but is untested) when /proc/devices >4096 bytes,
which I believe is what the original 2.6.16 rewrite fixed.
[akpm@osdl.org: cleanups, simplifications]
Signed-off-by: Joe Korty <joe.korty@ccur.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Commit a4a6198b80:
[PATCH] tvec_bases too large for per-cpu data
introduced "struct tvec_t_base_s boot_tvec_bases" which is visible at
compile time. This means we can kill __init_timer_base and move
timer_base_s's content into tvec_t_base_s.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
find_trylock_page() is an odd interface in that it doesn't take a reference
like the others. Now that XFS no longer uses it, and its last remaining
caller actually wants an elevated refcount, opencode that callsite and
schedule find_trylock_page() for removal.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
- chips/sharp.c: make two needlessly global functions static
- move some declarations to a header file where they belong to
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Acked-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Semaphore to mutex conversion.
The conversion was generated via scripts, and the result was validated
automatically via a script as well.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* 'upstream-linus' of master.kernel.org:/pub/scm/linux/kernel/git/jgarzik/libata-dev:
[PATCH] sata_mv: three bug fixes
[PATCH] libata: ata_dev_init_params() fixes
[PATCH] libata: Fix interesting use of "extern" and also some bracketing
[PATCH] libata: Simplex and other mode filtering logic
[PATCH] libata - ATA is both ATA and CFA
[PATCH] libata: Add ->set_mode hook for odd drivers
[PATCH] libata: BMDMA handling updates
[PATCH] libata: kill trailing whitespace
[PATCH] libata: add FIXME above ata_dev_xfermask()
[PATCH] libata: cosmetic changes in ata_bus_softreset()
[PATCH] libata: kill E.D.D.
This enables the caller to migrate pages from one address space page
cache to another. In buzz word marketing, you can do zero-copy file
copies!
Signed-off-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This adds support for the sys_splice system call. Using a pipe as a
transport, it can connect to files or sockets (latter as output only).
From the splice.c comments:
"splice": joining two ropes together by interweaving their strands.
This is the "extended pipe" functionality, where a pipe is used as
an arbitrary in-memory buffer. Think of a pipe as a small kernel
buffer that you can use to transfer data from one end to the other.
The traditional unix read/write is extended with a "splice()" operation
that transfers data buffers to or from a pipe buffer.
Named by Larry McVoy, original implementation from Linus, extended by
Jens to support splicing to files and fixing the initial implementation
bugs.
Signed-off-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add a field to the host_set called 'flags' (was host_set_flags changed
to suit Jeff)
Add a simplex_claimed field so we can remember who owns the DMA channel
Add a ->mode_filter() hook to allow drivers to filter modes
Add docs for mode_filter and set_mode
Filter according to simplex state
Filter cable in core
This provides the needed framework to support all the mode rules found
in the PATA world. The simplex filter deals with 'to spec' simplex DMA
systems found in older chips. The cable filter avoids duplicating the
same rules in each chip driver with PATA. Finally the mode filter is
neccessary because drive/chip combinations have errata that forbid
certain modes with some drives or types of ATA object.
Drive speed setup remains per channel for now and the filters now use
the framework Tejun put into place which cleans them up a lot from the
older libata-pata patches.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Some hardware doesn't want the usual mode setup logic running. This
allows the hardware driver to replace it for special cases in the least
invasive way possible.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
This is the minimal patch set to enable the current code to be used with
a controller following SFF (ie any PATA and early SATA controllers)
safely without crashes if there is no BMDMA area or if BMDMA is not
assigned by the BIOS for some reason.
Simplex status is recorded but not acted upon in this change, this isn't
a problem with the current drivers as none of them are for simplex
hardware. A following diff will deal with that.
The flags in the probe structure remain ->host_set_flags although Jeff
asked me to rename them, simply because the rename would break the usual
Linux rules that old code should break when there are changes. not
compile and run and then blow up/eat your computer/etc. Renaming this
later is a trivial exercise once a better name is chosen.
Signed-off-by: Jeff Garzik <jeff@garzik.org>
* git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc: (67 commits)
[PATCH] powerpc: Remove oprofile spinlock backtrace code
[PATCH] powerpc: Add oprofile calltrace support to all powerpc cpus
[PATCH] powerpc: Add oprofile calltrace support
[PATCH] for_each_possible_cpu: ppc
[PATCH] for_each_possible_cpu: powerpc
[PATCH] lock PTE before updating it in 440/BookE page fault handler
[PATCH] powerpc: Kill _machine and hard-coded platform numbers
ppc: Fix compile error in arch/ppc/lib/strcase.c
[PATCH] git-powerpc: WARN was a dumb idea
[PATCH] powerpc: a couple of trivial compile warning fixes
powerpc: remove OCP references
powerpc: Make uImage default build output for MPC8540 ADS
powerpc: move math-emu over to arch/powerpc
powerpc: use memparse() for mem= command line parsing
ppc: fix strncasecmp prototype
[PATCH] powerpc: make ISA floppies work again
[PATCH] powerpc: Fix some initcall return values
[PATCH] powerpc: Workaround for pSeries RTAS bug
[PATCH] spufs: fix __init/__exit annotations
[PATCH] powerpc: add hvc backend for rtas
...
Move 'tsk->sighand = NULL' from cleanup_sighand() to __exit_signal(). This
makes the exit path more understandable and allows us to do
cleanup_sighand() outside of ->siglock protected section.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This patch kills PIDTYPE_TGID pid_type thus saving one hash table in
kernel/pid.c and speeding up subthreads create/destroy a bit. It is also a
preparation for the further tref/pids rework.
This patch adds 'struct list_head thread_group' to 'struct task_struct'
instead.
We don't detach group leader from PIDTYPE_PID namespace until another
thread inherits it's ->pid == ->tgid, so we are safe wrt premature
free_pidmap(->tgid) call.
Currently there are no users of find_task_by_pid_type(PIDTYPE_TGID).
Should the need arise, we can use find_task_by_pid()->group_leader.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-By: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
__exit_signal() is private to release_task() now. I think it is better to
make it static in kernel/exit.c and export flush_sigqueue() instead - this
function is much more simple and straightforward.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Cosmetic, rename __exit_sighand to cleanup_sighand and move it close to
copy_sighand().
This matches copy_signal/cleanup_signal naming, and I think it is easier to
follow.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
__exit_signal() does important cleanups atomically under ->siglock. It is
also called from copy_process's error path. This is not good, for example we
can't move __unhash_process() under ->siglock for that reason.
We should not mix these 2 paths, just look at ugly 'if (p->sighand)' under
'bad_fork_cleanup_sighand:' label. For copy_process() case it is sufficient
to just backout copy_signal(), nothing more.
Again, nobody can see this task yet. For CLONE_THREAD case we just decrement
signal->count, otherwise nobody can see this ->signal and we can free it
lockless.
This patch assumes it is safe to do exit_thread_group_keys() without
tasklist_lock.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The only caller of exit_sighand(tsk) is copy_process's error path. We can
call __exit_sighand() directly and kill exit_sighand().
This 'tsk' was not yet registered in pid_hash[] or init_task.tasks, it has no
external references, nobody can see it, and
IF (clone_flags & CLONE_SIGHAND)
At least 'current' has a reference to ->sighand, this
means atomic_dec_and_test(sighand->count) can't be true.
ELSE
Nobody can see this ->sighand, this means we can free it
without any locking.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add lock_task_sighand() helper and converts group_send_sig_info() to use
it. Hopefully we will have more users soon.
This patch also removes '!sighand->count' and '!p->usage' checks, I think
they both are bogus, racy and unneeded (but probably it makes sense to
restore them as BUG_ON()s).
->sighand is cleared and it's ->count is decremented in release_task() with
sighand->siglock held, so it is a bug to have '!p->usage || !->count' after
we already locked and verified it is the same. On the other hand, an
already dead task without ->sighand can have a non-zero ->usage due to
ptrace, for example.
If we read the stale value of ->sighand we must see the change after
spin_lock(), because that change was done while holding that same old
->sighand.siglock.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This patch borrows a clever Hugh's 'struct anon_vma' trick.
Without tasklist_lock held we can't trust task->sighand until we locked it
and re-checked that it is still the same.
But this means we don't need to defer 'kmem_cache_free(sighand)'. We can
return the memory to slab immediately, all we need is to be sure that
sighand->siglock can't dissapear inside rcu protected section.
To do so we need to initialize ->siglock inside ctor function,
SLAB_DESTROY_BY_RCU does the rest.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
daemonize() calls set_special_pids(1,1), while init and kernel threads spawned
from init/main.c:init() run with 0,0 special pids. This patch changes
INIT_SIGNALS() so that that they run with ->pgrp == ->session == 1 also. This
patch relies on fact that swapper's pid == 1.
Now we have no hashed zero pids in pid_hash[].
User-space visibible change is that now /sbin/init runs with (1,1) special
pids and becomes a session leader.
Quoting Eric W. Biederman:
>
> daemonize consuming pids (1,1) then consumes pgrp 1. So that when
> /sbin/init calls setsid() it thinks /sbin/init is a process group
> leader and setsid() fails. So /sbin/init wants pgrp 1 session 1
> but doesn't get it. I am pretty certain daemonize did not exist so
> /sbin/init got pgrp 1 session 1 in 2.4.
>
> That is the bug that is being fixed.
>
> This patch takes things one step farther and essentially calls
> setsid() for pid == 1 before init is execed. That is new behavior
> but it cleans up the kernel as we now do not need to support the
> case of a process without a process group or a session.
>
> The only process that could have possibly cared was /sbin/init
> and it already calls setsid() because it doesn't want that.
>
> If this was going to break anything noticeable the change in behavior
> from 2.4 to 2.6 would have already done that.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
fork_idle() does unhash_process() just after copy_process(). Contrary,
boot_cpu's idle thread explicitely registers itself for each pid_type with nr
= 0.
copy_process() already checks p->pid != 0 before process_counts++, I think we
can just skip attach_pid() calls and job control inits for idle threads and
kill unhash_process(). We don't need to cleanup ->proc_dentry in fork_idle()
because with this patch idle threads are never hashed in
kernel/pid.c:pid_hash[].
We don't need to hash pid == 0 in pidmap_init(). free_pidmap() is never
called with pid == 0 arg, so it will never be reused. So it is still possible
to use pid == 0 in any PIDTYPE_xxx namespace from kernel/pid.c's POV.
However with this patch we don't hash pid == 0 for PIDTYPE_PID case. We still
have have PIDTYPE_PGID/PIDTYPE_SID entries with pid == 0: /sbin/init and
kernel threads which don't call daemonize().
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Both SET_LINKS() and SET_LINKS/REMOVE_LINKS() have exactly one caller, and
these callers already check thread_group_leader().
This patch kills theese macros, they mix two different things: setting
process's parent and registering it in init_task.tasks list. Callers are
updated to do these actions by hand.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
add_parent(p, parent) is always called with parent == p->parent, and it makes
no sense to do it differently. This patch removes this argument.
No changes in affected .o files.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
switch_exec_pids is only called from de_thread by way of exec, and it is
only called when we are exec'ing from a non thread group leader.
Currently switch_exec_pids gives the leader the pid of the thread and
unhashes and rehashes all of the process groups. The leader is already in
the EXIT_DEAD state so no one cares about it's pids. The only concern for
the leader is that __unhash_process called from release_task will function
correctly. If we don't touch the leader at all we know that
__unhash_process will work fine so there is no need to touch the leader.
For the task becomming the thread group leader, we just need to give it the
pid of the old thread group leader, add it to the task list, and attach it
to the session and the process group of the thread group.
Currently de_thread is also adding the task to the task list which is just
silly.
Currently the only leader of __detach_pid besides detach_pid is
switch_exec_pids because of the ugly extra work that was being
performed.
So this patch removes switch_exec_pids because it is doing too much, it is
creating an unnecessary special case in pid.c, duing work duplicated in
de_thread, and generally obscuring what it is going on.
The necessary work is added to de_thread, and it seems to be a little
clearer there what is going on.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Kirill Korotaev <dev@sw.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
The kill_sl function doesn't exist in the kernel so a prototype is completely
unnecessary.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* master.kernel.org:/home/rmk/linux-2.6-serial:
[SERIAL] Provide Cirrus EP93xx AMBA PL010 serial support.
[SERIAL] amba-pl010: allow platforms to specify modem control method
[SERIAL] Remove obsoleted au1x00_uart driver
[SERIAL] Small time UART configuration fix for AU1100 processor
* 'cfq-merge' of git://brick.kernel.dk/data/git/linux-2.6-block:
[BLOCK] cfq-iosched: seek and async performance fixes
[PATCH] ll_rw_blk: fix 80-col offender in put_io_context()
[PATCH] cfq-iosched: small cfq_choose_req() optimization
[PATCH] [BLOCK] cfq-iosched: change cfq io context linking from list to tree
Fix a lot of typos. Eyeballed by jmc@ in OpenBSD.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Replace all occurences of 0xff.. in calls to function pci_set_dma_mask()
and pci_set_consistant_dma_mask() with the corresponding DMA_xBIT_MASK from
linux/dma-mapping.h.
Signed-off-by: Matthias Gehre <M.Gehre@gmx.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This is a conversion to make the various file_operations structs in fs/
const. Basically a regexp job, with a few manual fixups
The goal is both to increase correctness (harder to accidentally write to
shared datastructures) and reducing the false sharing of cachelines with
things that get dirty in .data (while .rodata is nicely read only and thus
cache clean)
Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Mark the f_ops members of inodes as const, as well as fix the
ripple-through this causes by places that copy this f_ops and then "do
stuff" with it.
Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
for_each_cpu() is a for-loop over cpu_possible_map. for_each_online_cpu is
for-loop cpu over cpu_online_map. .....for_each_cpu() is not sufficiently
explicit and can lead to mistakes.
This patch adds for_each_possible_cpu() in preparation for the removal of
for_each_cpu().
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Optimize select and poll by a using stack space for small fd sets
This brings back an old optimization from Linux 2.0. Using the stack is
faster than kmalloc. On a Intel P4 system it speeds up a select of a
single pty fd by about 13% (~4000 cycles -> ~3500)
It also saves memory because a daemon hanging in select or poll will
usually save one or two less pages. This can add up - e.g. if you have 10
daemons blocking in poll/select you save 40KB of memory.
I did a patch for this long ago, but it was never applied. This version is
a reimplementation of the old patch that tries to be less intrusive. I
only did the minimal changes needed for the stack allocation.
The cut off point before external memory is allocated is currently at
832bytes. The system calls always allocate this much memory on the stack.
These 832 bytes are divided into 256 bytes frontend data (for the select
bitmaps of the pollfds) and the rest of the space for the wait queues used
by the low level drivers. There are some extreme cases where this won't
work out for select and it falls back to allocating memory too early -
especially with very sparse large select bitmaps - but the majority of
processes who only have a small number of file descriptors should be ok.
[TBD: 832/256 might not be the best split for select or poll]
I suspect more optimizations might be possible, but they would be more
complicated. One way would be to cache the select/poll context over
multiple system calls because typically the input values should be similar.
Problem is when to flush the file descriptors out though.
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Some quick backport bits from the libata PATA work to fix things found in
the sis driver. The piix driver needs some fixes too but those are way to
large and need someone working on old IDE with time to do them.
This patch fixes the case where random bits get loaded into SIS timing
registers according to the description of the correct behaviour from
Vojtech Pavlik. It also adds the SiS5517 ATA16 chipset which is not
currently supported by the driver. Thanks to Conrad Harriss for loaning me
the machine with the 5517 chipset.
Signed-off-by: Alan Cox <alan@redhat.com>
Acked-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add proper prototypes for fat_cache_init() and fat_cache_destroy() in
msdos_fs.h.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
On ppc64 we look at a profiling register to work out the sample address and
if it was in userspace or kernel.
The backtrace interface oprofile_add_sample does not allow this. Create
oprofile_add_ext_sample and make oprofile_add_sample use it too.
Signed-off-by: Anton Blanchard <anton@samba.org>
Cc: Philippe Elie <phil.el@wanadoo.fr>
Cc: John Levon <levon@movementarian.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add driver support for general purpose I/O feature of the Synclink GT
adapters.
Signed-off-by: Paul Fulghum <paulkf@micrgate.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Detect whether a given process is seeky and if so disable (mostly) the
idle window if it is. We still allow just a little idle time, just enough
to allow that process to submit a new request. That is needed to maintain
fairness across priority groups.
In some cases, we could setup several async queues. This is not optimal
from a performance POV, since we want all async io in one queue to perform
good sorting on it. It also impacted sync queues, as async io got too much
slice time.
Signed-off-by: Jens Axboe <axboe@suse.de>
On setups with many disks, we spend a considerable amount of time
looking up the process-disk mapping on each queue of io. Testing with
a NULL based block driver, this costs 40-50% reduction in throughput
for 1000 disks.
Signed-off-by: Jens Axboe <axboe@suse.de>
