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	Spinlock - Wikipedia, the free encyclopedia
		Spinlocks are efficient if threads are only likely to be blocked for a short period of time, as they avoid overhead from operating system process re-scheduling.
		Implementing spinlocks is difficult, because one must take account of the possibility of simultaneous access to the lock to prevent race conditions.
		Solaris will use a spinlock when trying to access a resource locked by a currently-running thread, but will sleep if the thread is not currently running (which always happens on single-processor systems).
	en.wikipedia.org /wiki/Spinlock (901 words)

	Spinlocks (Site not responding. Last check: 2007-10-21)
		Spinlocks are a more fundamental way of protecting critical sections than semaphores, in that they are used in the construction of the semaphore services; semaphore implementations themselves are critical sections.
		Spinlocks must be held for as short a time as possible (preferably less than the time it takes to make one context switch).
		Spinlocks are used to guarantee access to global data structures by a single thread of execution.
	docs.hp.com /en/5965-4643/ch01s07.html (916 words)

	Spinlocks
		Spinlock's do not use the processor very efficiently since theycontinuously execute code until spinlock is owned.
		Spinlock's do have the advantagethat they do not cause a transfer to the operating system, which can be slow, andthey do not allocate any operating system resources.
		If the spinlock is already owned placinga one in the spinlock is harmless since a value of 1 was already in the spinlock.
	www.modula2.org /sb/websitearchive/env/index34.htm (462 words)

	[No title]
		Spinlocks are mutually exclusive locks that are used to protect sections of code that must execute atomically.
		The spinlock should be held as briefly as possible, and acquisition must not be nested within the critical section.
		Spinlocks are designed for use in a multi-processor system (on a single processor system simply turning off interrupts is enough to guarantee that the critical section will be atomic).
	www.beunited.org /bebook/Drivers/KernelFunctions.html (1419 words)

	SGI - Developer Central Open Source \| Lockmeter
		Data displayed includes the number of lock attempts, per-spinlock per-caller, the number of those attempts that were immediately successful vs. those that required the attempting locker to wait for the current lock-holder to release; the mean and max hold-time, and the mean, max, and cumulative wait-time.
		Whenever possible, the locking caller and the spinlocks are identified by their symbolic names, not by their virtual addresses.
		Compiling the spinlock metering code into the kernel does not materially affect the kernel size because the additional code is roughly compensated for by the shrinking effect of the normally in-line locking routines now becoming procedure calls.
	oss.sgi.com /projects/lockmeter (666 words)

	CIS 307: SpinLocks and Semaphores
		A big problem of the spinlock is that by repeatedly testandsetting a location in memory it can use a high percentage of the memory bus bandwidth, thus reducing the utilization of other procesors sharing the memory bus.
		In general spinlocks with their busy waiting mechanism are desirable (as compared to non busy waiting mechanisms like semaphores) when the scheduling and context switching time are greater than the time required to execute the critical region, or when there are processors not required to do other tasks.
		Boolean semaphores are the non-busy-waiting analogs of spinlocks.
	www.cis.temple.edu /~ingargio/cis307/readings/spinsem.html (1633 words)

	Synchronization and locking on HP-UX - HP DSPP (Site not responding. Last check: 2007-10-21)
		Assuming that the scheduler spinlock is currently held, the process spinlock may be acquired, but if the process spinlock is held, then the scheduler spinlock may not be acquired.
		Since the spinlock is the primary form of synchronization in the kernel, there are many spinlocks used throughout the kernel.
		Unlike spinlocks, semaphores cause threads which are waiting to acquire the lock, to relinquish the CPU and allow another thread to run.
	h21007.www2.hp.com /dspp/tech/tech_TechDocumentDetailPage_IDX/1,1701,2540,00.html (3872 words)

	Spinlock Store: Rope Clutches, Cleats and more
		Spinlock is dedicated to providing deck hardware, rope clutches and sailboat equipment to sailboat builders, spar manufacturers and high performance racing yacht projects, as well as to the club PHRF and IRC sailboat and Grand Prix racer.
		An important part of the Spinlock Powerclutch design (but not for the ZS jammer) has always been to try and ease the load at this limit, rather than break the cover but this becomes increasingly difficult to achieve with smaller diameters due to the high point loading.
		If you need immediate assistance finding the appropriate Spinlock sailboat hardware, deckware or any other sailing equipment for your boat, please call us toll free at: 1-866-766-6264, our crew is ready to help you.
	www.mauriprosailing.com /spinlock.htm (616 words)

	CVS log for src/sys/sys/spinlock2.h
		This also has the effect of relaxing the requirement that further exclusive spinlocks cannot be acquired while holding a shared spinlock, but for now we are going to leave the requirement intact.
		Spinlocks cannot be used for this purpose on UP because they are coded to a degenerate case on a UP build.
		On a UP build an explicit preemption check is needed, but no spinlock or per-thread counter is required because the definition of a token is that it is only 'held' while a thread is actually running or preempted.
	www.dragonflybsd.org /cvsweb/src/sys/sys/spinlock2.h?f=h (1406 words)

	pthread_spin_lock (Site not responding. Last check: 2007-10-21)
		Spinlocks are a thread synchronization device to protect critical code sections from concurrent execution in a multi-processor environment.
		To allow spinlocks to protect data that are modified by interrupt handlers, and to use the spinlock functions also in interrupt handlers, local interrupts are disabled when a thread acquires a spinlock.
		Spinlocks should therefore be locked only for short periods of time.
	www.cc.gatech.edu /classes/AY2003/cs6235_spring/project1/doc/html/MAN/pthread_spin_destroy.3.html (268 words)

	Kernel Locking Techniques \| Linux Journal
		A final variation of the spinlock is spin_lock_bh() that implements the standard spinlock as well as disables softirqs.
		Spinlocks should be used to lock data in situations where the lock is not held for a long time--recall that a waiting process will spin, doing nothing, waiting for the lock.
		The reader/writer spinlock is called an rwlock and is used similarly to the standard spinlock, with the exception of separate reader/writer locking:
	www.linuxjournal.com /article.php?sid=5833 (3288 words)

	Spinlock Pool Parameters (Site not responding. Last check: 2007-10-21)
		These parameters are for use by advanced users only who have a thorough understanding of how spinlocks are used by multiple processors and how the number of spinlocks needed are related to system size and complexity.
		In simple terms, spinlocks are a mechanism used in multiple-processor systems to control the interaction of processors that must be held off while waiting for another processor to finish a task so the results can be passed to the waiting processor.
		In general, if the system is encountering lock contention problems that are associated with one of these hashed pools, first identify the resource spinlock pool that is associated with the contention, then increase the spinlock pool parameter for that resource.
	docs.hp.com /en/TKP-90203/ch09s02.html (372 words)

	APS: Cleats, Jammers and Clutches (Site not responding. Last check: 2007-10-21)
		The XAS Powerclutch is an effortless multi-role clutch and the new sucessor to the Spinlock XA series.
		Spinlock XAS replacement parts and accessories are available for upgrades and repairs.
		The Spinlock XC Clutch is the high-load version of the XT Clutch.
	www.apsltd.com /Tree/d3000/e3.asp (1189 words)

	Nance Underwood Sails and Riggging Spinlock
		Spinlock offers a large array of quality marine hardware for many uses.
		Spinlock clutches have the ability to hold loads up to 1800kgs and can take a vast rope range without having to change any parts of the clutch.
		Spinlock "aft" organisers and winch feeders divert several lines from clutches or jammers, to enable a choice of winching positions and an optimum deck layout.
	www.riggingandsails.com /products-spinlock.html (404 words)

	spinlock xts clutch - Sailing Anarchy Forums
		the spinlock xts clutches come in two sizes - one for 1/4 to 5/16 line (swl=1540lbs), and one for 5/16 to 9/16 line (swl=2200lbs).
		I had brand new Marlow D2 Racing for all of my halyards, which was perfectly rated for mid range of a Spinlock XAS, it was 8mm line in a 6-12mm clutch on a 27' racing boat.
		Good news was Spinlock was absolutely great about it, sent me new XTS clutches, worked with Marlow to replace the halyards at no charge, and even followed up to see how it was going.
	www.sailinganarchy.com /forums/index.php?showtopic=16557 (962 words)

	EDM/2 - SMP - Symmetrical Multiprocessing
		If the spinlock is available most of the time, requesting and releasing a spinlock usually only involves executing 50 instructions.
		When the spinlock is requested and it is not already owned by a thread, very few instructions are executed, say 5-10 instructions.
		When a spinlock owned by a thread is released one of the waiting threads obtains the spinlock in a matter of nanoseconds.
	www.edm2.com /0507/smp.html (2312 words)

	Have some user space spinlock code... - UNIX Socket FAQ
		Parameters: spin - a pointer to the spinlock structure to be initialized.
		But what I meant is that it shouldn't be needed because synchronizing all spinlock initializations and destroys is a bit overkill for something which can be avoid easily by the programmer using the spinlocks.
		If they want to initialize and/or destroy the same spinlock in parallel then they can provide their own synchronisation, it should be a rare case.
	www.developerweb.net /forum/showthread.php?p=18927 (3753 words)

	Weightlifting Equipment
		They have a chromed finish to prevent rusting, and the handles are knurled for extra grip.
		Spinlock bars have threaded ends and outside collars for a swifter changeover when adding or removing discs.
		Spring collars are for barbells or dumbells and are quick to put on or remove.
	www.worldofhealthandleisure.co.uk /weightsbarbellsdumbells.htm (352 words)

	Reliquary Class Library (Site not responding. Last check: 2007-10-21)
		Spinlocks are similar to Mutex objects, except for the following restrictions:
		Since Spinlocks only exist in the process where they were created, they are typically faster than a Mutex.
		When a Spinlock is locked, other threads are unable to acquire the lock.
	www.fidnet.com /~bbreeden/reliquary/classlib/spinlock.htm (179 words)

	HoppeRx - the cure for your ailing device : Some threads are stuck in the Sql SpinLock: why?
		The spinlock implementation is entirely unrelated to the synchronization mechanisms provided by the kernel as primitives (such as critical sections), the kernel is unaware of any spinlocks and it doesn’t know that such code portion is actually protecting a serialized area.
		Since the kernel is unaware of that, it cannot apply any of the contingency measures (such as priority inversion) that are applied to the default synchronization objects.
		The kernel would invert the priorities granting T3 with T4’s priority preventing the starvation; however, since that is not the case (the spinlock doesn’t support priority inversion) we need to ensure that no thread will cause starvation in the system.
	blogs.msdn.com /hopperx/archive/2006/03/31/566056.aspx (781 words)

	EXPO21XX - Spinlock
		As an independent specialist company, Spinlock are the acknowledged world leaders in rope holding technology.
		Building on 30 years of experience, we are evolving new technology which is changing the whole concept of sailing - for the better.
		If you are already a Spinlock owner, take a look at the technical support section, with the latest advice on installation, servicing and upgrading for each piece of Spinlock equipment.
	www.expo21xx.com /popup/6637.htm (167 words)

	CriticalSection vs Spinlock vs MutexSem (Site not responding. Last check: 2007-10-21)
		The spinlock is the least flexible of the three, but it is alsofastest.
		A CriticalSectionis a hybrid of a spinlock and a MutexSem.
		It will spin for a number iterations attemptingto obtain the lock, and then efficiently wait if the lock could not be obtained.The spinlock portion does not require a transition to the operating system, and thisis why a CriticalSection is fast.
	www.modula2.org /sb/websitearchive/env/index35.htm (345 words)

	The Windows Driver Model Simplifies Management of Device Driver I/O Requests MSJ, January 1999
		This prevents the extremely unlikely scenario in which between releasing the cancel spinlock and acquiring the local spinlock, the IRP in question is removed from the queue, completed, reallocated, reinserted back onto the same queue, and then cancelled, resulting in two threads in IrpCancelRoutine that will complete the same IRP.
		Your local spinlock is the only thing preventing the IRP from being freed between the time EnqueueIrp sets the cancel routine and the time it checks the Cancel flag (or between checking the Cancel flag and queuing the IRP, depending on your implementation).
		If a function is not an ISR or a DPC, and it does not execute while holding a spinlock (it is not called from code that holds a spinlock and does not acquire a spinlock itself), then you can make your driver a better citizen by making that function pageable.
	www.microsoft.com /msj/0199/windowsdriver/windowsdriver.aspx (4891 words)

	QNX Developer Support
		PTHREAD_PROCESS_SHARED -- the spinlock may be operated on by any thread that has access to the memory where the spinlock is allocated, even if it's allocated in memory that's shared by multiple processes.
		The pthread_spin_init() function allocates the resources required for the thread spinlock spinner, and initializes spinner to an unlocked state.
		The process spinlock, spinner, is in use by another thread and can't be initialized.
	www.qnx.com /developers/docs/6.3.0/neutrino/lib_ref/p/pthread_spin_init.html (219 words)

	OSR's ntfsd List: kernel spinlock/executive question
		I need this cuz I hold the spinlock while searching through a linked list and once match is found I would like to grab the executive resource of the matched node.
		Since you are using spinlock to protect the list you are not taking advantage of eresource here.
		I need this cuz I hold the > spinlock while searching through a linked list and once match is found > I would like to grab the executive resource of the matched node.
	www.osronline.com /showThread.cfm?link=4879 (718 words)

	Spinlocks: Part II (Site not responding. Last check: 2007-10-21)
		the last spinlock's level that was locked by this cpu.
		So if a cpu has one of the low priority spinlocks, it is running with hardware interrupt delivery enabled (but the pre-emptive scheduler is disabled).
		Well, you can imagine then, that what you end up with is having just one cpu doing anything useful at a time in kernel mode, while the other(s) just grind away spinning.
	osdev.berlios.de /spinlock_part2.html (747 words)

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