| Age | Commit message (Collapse) | Author |
|---|
|
This patch removes all the wait_queue handling code from sched.h and puts
it in wait.h with the rest of the wait_queue handling code. Note that
sched.h must continue to include wait.h for the wait_queue_head_t embedded
in struct task. However there may be files which only need wait.h now.
|
|
This is worth a whopping 2% on spwecweb on an 8-way. Which is faintly
surprising because __wake_up and other wait/wakeup functions are not
apparent in the specweb profiles which I've seen.
The main objective of this is to reduce the CPU cost of the wait/wakeup
operation. When a task is woken up, its waitqueue is removed from the
waitqueue_head by the waker (ie: immediately), rather than by the woken
process.
This means that a subsequent wakeup does not need to revisit the
just-woken task. It also means that the just-woken task does not need
to take the waitqueue_head's lock, which may well reside in another
CPU's cache.
I have no decent measurements on the effect of this change - possibly a
20-30% drop in __wake_up cost in Badari's 40-dds-to-40-disks test (it
was the most expensive function), but it's inconclusive. And no
quantitative testing of which I am aware has been performed by
networking people.
The API is very simple to use (Linus thought it up):
my_func(waitqueue_head_t *wqh)
{
DEFINE_WAIT(wait);
prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
if (!some_test)
schedule();
finish_wait(wqh, &wait);
}
or:
DEFINE_WAIT(wait);
while (!some_test_1) {
prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
if (!some_test_2)
schedule();
...
}
finish_wait(wqh, &wait);
You need to bear in mind that once prepare_to_wait has been performed,
your task could be removed from the waitqueue_head and placed into
TASK_RUNNING at any time. You don't know whether or not you're still
on the waitqueue_head.
Running prepare_to_wait() when you're already on the waitqueue_head is
fine - it will do the right thing.
Running finish_wait() when you're actually not on the waitqueue_head is
fine.
Running finish_wait() when you've _never_ been on the waitqueue_head is
fine, as ling as the DEFINE_WAIT() macro was used to initialise the
waitqueue.
You don't need to fiddle with current->state. prepare_to_wait() and
finish_wait() will do that. finish_wait() will always return in state
TASK_RUNNING.
There are plenty of usage examples in vm-wakeups.patch and
tcp-wakeups.patch.
|
|
These are the completely generic bits (linux/init_task.h and linux/wait.h).
From: Art Haas <ahaas@neosoft.com>
Here's the latest diffs for the files in include/linux.
Patches are against 2.5.31.
|
|
This adds support for wait queue function callbacks, which are used by
aio to build async read / write operations on top of existing wait
queues at points that would normally block a process.
|
|
This patch removes the whole wq_lock_t abstraction, forcing the behavior
to be that of a standard spinlock and changes all the wq_lock code in
the tree appropriately.
Removes lots of code - always a Good Thing to me. New behavior is same
as previous behavior (USE_RW_WAIT_QUEUE_SPINLOCK unset).
|
|
- Jens Axboe: more bio updates, fix some request list bogosity under load
- Al Viro: export seq_xxx functions
- Manfred Spraul: include file cleanups, pc110pad compile fix
- David Woodhouse: fix JFFS2 write error handling
- Dave Jones: start merging up with 2.4.x patches
- Manfred Spraul: coredump fixes, FS event counter cleanups
- me: fix SCSI CD-ROM sectorsize BIO breakage
|
|
- Russell King: /proc/cpuinfo for ARM
- Paul Mackerras: PPC update (cpuinfo etc)
- Nicolas Aspert: fix Intel 8xx agptlb flush
- Marko Myllynen: "Lindent" doesn't really need bash ;)
- Alexander Viro: /proc/cpuinfo for s390/s390x/sh, /proc/pci cleanup
- Alexander Viro: make lseek work on seqfiles
|
|
- Greg KH: start migration to new "min()/max()"
- Roman Zippel: move affs over to "min()/max()".
- Vojtech Pavlik: VIA update (make sure not to IRQ-unmask a vt82c576)
- Jan Kara: quota bug-fix (don't decrement quota for non-counted inode)
- Anton Altaparmakov: more NTFS updates
- Al Viro: make nosuid/noexec/nodev be per-mount flags, not per-filesystem
- Alan Cox: merge input/joystick layer differences, driver and alpha merge
- Keith Owens: scsi Makefile cleanup
- Trond Myklebust: fix oopsable race in locking code
- Jean Tourrilhes: IrDA update
|
|
- Chris Mason: daemonize reiserfs commit thread
- Alan Cox: syncup (AFFS might even work, and official VIA workarounds)
- Jeff Garzik: network driver updates
- Paul Mackerras: PPP update
- David Howells: more rw-sem cleanups, updates. Slowly getting somewhere.
|
|
- Ingo Molnar/Al Viro: don't use bforget() on ext2 (and minix) metadata
where we may not be the only owner of the buffer! FS corruption.
- Andi Kleen: IPv6 packet re-assembly fix.
- David Howells: fix up rwsem implementation
- Alan Cox: more merging (S/390 down, ARM to go).
- Jens Axboe: LVM and loop fixes
|
|
- driver sync up with Alan
- Andrew Morton: wakeup cleanup and race fix
- Paul Mackerras: macintosh driver updates.
- don't trust "page_count()" on reserved pages!
- Russell King: fix serious IDE multimode write bug!
- me, Jens, others: fix elevator problem
- ARM, MIPS and cris architecture updates
- alpha updates: better page clear/copy, avoid kernel lock in execve
- USB and firewire updates
- ISDN updates
- Irda updates
|
|
|
