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Topic: Busy waiting

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	[No title]
		From this we concluded that the buffer busy waits appeared related to the single block disk reads—buffer block reads were waiting for other buffer block reads to complete, and those in turn were waiting for sequential reads from disk to complete.
		This was the longest buffer busy wait for this statement, as indicated by the “Max.
		Waits on db file sequential read and db file scattered read combined were significantly shorter than the waits on db file sequential read in the original query because large numbers of single block I/Os were replaced with fewer multi-block I/Os.
	www.dbspecialists.com /presentations/wait_events2.doc (9809 words)

	Monitor (synchronization) - Wikipedia, the free encyclopedia
		To avoid entering a busy waiting state, processes must be able to signal each other about events of interest.
		Note that since waiting on a condition forfeits the lock, the waiter must make sure the monitor invariant is satisfied before it waits.
		In early monitor implementations, notifying a condition variable caused a waiting process to receive the lock and run immediately, thereby guaranteeing that the condition would still be true.
	en.wikipedia.org /wiki/Condition_variable (774 words)

	[No title] (Site not responding. Last check: 2007-11-04)
		On a uniprocessor, busy waiting is wasteful of cpu cycles.
		On a multiprocessor, busy waiting is not as wasteful and may be an option for short waits.
		The introduction of busy waiting appeared to solve the original problem of the two threads - the "producer" that incremented x and the "consumer", that printed each new value of x.
	condor.depaul.edu /~glancast/343class/docs/lecJan26.html (1413 words)

	servicing.html
		If busy processors reject requests as they arrive, then we have to reject the second request, if it comes within the time it takes to serve the first request.
		When all processors are busy, we assign the job to the processor with the smallest service time.
		The waiting time for this job is then the service time the processor had at the time of assignment.
	www.math.uic.edu /~jan/mcs494f02/Lec5/servicing1.html (599 words)

	CSci 444/544, Fall 2005 Homework #1 (Site not responding. Last check: 2007-11-04)
		One of pros of busy waiting is that it is efficient in cases where the expected wait time is less than the overhead of context switching out of and back to the waiting thread.
		By definition a busy wait just spins on the CPU until the lock becomes available, and perhaps these cycles could be used for some other computation.
		Busy waiting can be avoided in a synchronization primitive if the primitive always performs a yield whenever an unavailable lock is needed.
	www.cs.wm.edu /~dsn/courses/444/homework/hw1sol.html (1843 words)

	Semaphore (programming) - Open Encyclopedia (Site not responding. Last check: 2007-11-04)
		The P and V operations must be indivisible, which means that each of the operations may not be executed multiple times concurrently.
		A process wishing to execute an operation that is already being executed by another process must wait for it to complete first.
		The V operation is sometimes known as "up", and the P operation as "down".
	open-encyclopedia.com /Semaphore_(programming) (455 words)

	Busy Waiting
		The algorithm is that each process should first wait for all other processes to clear their critical sections, then declare their own intention to enter (the intention being to exclude all other processes from entering), then enter, then relinquish their intention after clearing the critical section.
		The problem is that after waiting for all other processes to clear their critical sections a process may not be able to get into theirs before another process does so.
		While waiting a process should not be eternally insistent, but rather graciously give others the opportunity to enter their critical section first.
	www.dcs.warwick.ac.uk /~sgm/cs237/lec/busy (1149 words)

	CS411/511 - Homework (Site not responding. Last check: 2007-11-04)
		Busy waiting: A process is waiting for an event to occur and it does so by executing instructions.
		Other types of waiting: A process is waiting for an event to occur in some waiting queue (e.g., I/O semaphore) and it does so without having the CPU assigned to it.
		To prove bounded waiting, we note that whenever a process leaves its critical section, it checks to see if any other processes want to enter their critical sections.
	web.engr.oregonstate.edu /~pancake/cs411/hw4sol.s99.html (1184 words)

	[SDL] bomber busy waiting? (Site not responding. Last check: 2007-11-04)
		If you wanted to wait As regards the sound stuff there is no busy waiting in my code, it is just the SDL audio callback that I wrote.
		At the start the code checks for audio commands and adds each requested audio sample to the list of active samples, then when there are no more commands in the queue, the code actually sums the commands and fills in the audio buffer.
		It doesn't wait until a command is received, it just deals with commands that are already there ready to be processed.
	www.libsdl.org /pipermail/sdl/1999-July/021398.html (347 words)

	CS67 Operating Systems
		Busy Waiting / Blocking Busy waiting and blocking are both ways a process can wait for an event to occur.
		Blocking is a much better way to wait for an event since it does not consume CPU cycles like busy waiting does.
		If a writer is waiting (no_writer_waiting = 0), this down operation will cause the reader to wait until the writer gets control of the database.
	www.cs.siena.edu /~flatland/exam1sol.html (701 words)

	Skycasters Broadband Satellite Internet-Dealer Information
		Every day, companies turn to the Internet to match the changing business practices of their suppliers and customers, who are choosing to conduct as much business as possible over the Internet as a way to reduce operating and sales costs.
		Businesses are continuing to increase their use of the Internet for e-commerce, email, a research and reference source for any subject, a travel agent, a stock ticker, an encyclopedia, a worldwide phone book and much, much more.
		This tremendous increase in business Internet access is the result of a continuing nationwide landslide of businesses seeking always-on, high-speed Internet connections that can be shared among multiple users in a single office.
	www.skycasters.com /dealer-info.html (726 words)

	IBM Redbooks \| XES Coupling Facility Subchannel Tuning (Site not responding. Last check: 2007-11-04)
		The effect of this should be that when a request is started, rather than being given a subchannel and then spinning waiting for a link buffer to become available, the request may receive subchannel busy (because fewer subchannels are available) and the request will be converted to an asynchronous request.
		Because MVSW is receiving a higher percentage of path busy conditions (about 400%!), XES on MVSW has varied 4 of its subchannels offline in an effort to reduce the amount of time it is receiving path busy when it tries to use one of the links.
		If the high PATH BUSY events are primarily on the links to one CF, consider moving some of the busier structures from that CF to one with lower utilization.
	www.redbooks.ibm.com /Redbooks.nsf/ffb155b535b4144485256c050061937a/c533df2d6aedfb8d85256d25004cf328?OpenDocument&printable (1140 words)

	[No title]
		Processes that are busy waiting use their whole quantum doing nothing (if they're waiting, the process actually in its critical section can't be advancing...).
		Not only can busy waiting be inconvenient, on systems with a priority scheduler priority inversions can occur.
		Processes waiting to enter a critical section will be put in the blocked state, just like they were waiting for I/O, so that other processes can continue doing useful work.
	www.isi.edu /~faber/cs402/notes/lecture7.html (1687 words)

	[No title]
		If wait is expected to be short, busy waiting is used in form of a spin lock.
		The solution using TSL is correct, but does require the use of busy waiting.
		Mutex lock is particularly useful for threads because it is not busy waiting.
	grail.cba.csuohio.edu /~jackie/cis345a/notes/cis34508.txt (1145 words)

	More Examples of Interpreting Wait Events to Boost System Performance - Part I
		The session is waiting for the opportunity to load an object or a piece of an object into the library cache.
		The session is waiting for a requested buffer to be written to disk; the buffer cannot be used while it is being written.
		There are several wait events that we call "idle events" because each of these wait events typically occurs when the Oracle process has nothing to do and is waiting for somebody to give it a task.
	www.revealnet.com /newsletter-v4/0503_A.htm (2661 words)

	Interpreting Wait Events
		The session is waiting for an undo segment to be extended or shrunk.
		Following the same approach as used with the buffer busy waits, we then drilled down to find which segments in the database sessions were accessing with the single block I/Os.
		From this we concluded that the buffer busy waits appeared related to the single block disk reads-buffer block reads were waiting for other buffer block reads to complete, and those in turn were waiting for sequential reads from disk to complete.
	www.pafumi.net /Wait_Events.html (13569 words)

	index.html (Site not responding. Last check: 2007-11-04)
		Busy Waiting: If a process is denied access to its critical section, it will continue to check again and again until it can enter its critical section.
		This continuous checking of the lock variable is called busy waiting.
		Busy waiting waste valuable processor time, and in some cases can cause deadlock.
	www.ualr.edu /xxliu3/thirdp.htm (172 words)

	[No title]
		Also, inside the waiting loop, interrupts are enabled first so that someone else may have a chance to release the lock.
		However, as soon as the lock regains the control inside the loop, interrupts are disabled again before checking the status of the lock.
		Although this approach works for uniprocessors, on a multiprocessor, interrupt disable does not provide atomicity because stopping context switching from occurring on one CPU does not stop other CPUs from entering the critical section.
	www.cs.fsu.edu /~awang/courses/cs111/lecture_6_mutual_exclusion.doc (449 words)

	Busy Waiting (Site not responding. Last check: 2007-11-04)
		In other words, as long as a process is denied access to its critical section, it will stay in a tight loop and wait until it can proceed, all the while wasting processor time.
		This continuous testing of the lock variable is called busy waiting.
		Mutual exclusion policies that require busy waiting waste valuable processor time, and in some cases can lead to situations where a process will test the lock variable forever, a very undesirable occurence.
	cne.gmu.edu /modules/ipc/red/busy.html (559 words)

	Manual page for drv_usecwait(9F) (Site not responding. Last check: 2007-11-04)
		First, the granularity of the wait time is limited to one clock tick, which may be more time than is needed for the delay.
		Second, delay(9F) may only be invoked from user context and hence cannot be used at interrupt time or system initialization.
		Often, drivers need to delay for only a few microseconds, waiting for a write to a device register to be picked up by the device.
	www.cs.utk.edu /~cs460.is&r/cgi-bin/group4/collection/drv_usecwait.9f.html (182 words)

	CS 162 Sec 101 Spring 2002: Notes 19 Feb
		In a priority-based CPU scheduler, the waiting thread might be higher priority while the lock holder might be lower priority, so that lock holder never gets to run and release the lock.
		Keep busy waiting to a minimum; don’t busy wait for the entire time someone else holds the lock, just busy wait for enough time to tell that someone else holds the lock by checking a guard variable.
		This donation should propagate to thread 1 since thread 2 is waiting on it, so that both thread 2 and 1 should have an effective priority of 3.
	www.ocf.berkeley.edu /~jerylkat/cs162/cs162_101notes19feb.html (1367 words)

	[No title]
		The initial value should be 0, and the absolute value of the semaphore represents the number of processes waiting.
		Do not release mutex, as it is being "granted" to the waiting process.
		If context switch occurs between " busy = FALSE " and " if wait_to_read then V(rdr) ", and if a writer comes and gets CPU, it will enter the C.S. because readcount = 0 and busy = false.
	www.ee.umd.edu /courses/enee648i/race.txt (1283 words)

	3.2.0.1 Synchronized methods and statements (Site not responding. Last check: 2007-11-04)
		The writer may be reawakened when the reader reads some data and the routine for reading from the buffer determines that there is available space for more data to be written.
		We can program a Java thread so that it busy waits on a locked object, but this is almost always a bad programming practice.
		puts the calling thread to sleep on a queue of threads that are waiting for some change in the status of a locked object.
	www.cs.rice.edu /~cork/teachjava/2003/notes/current/node97.html (513 words)

	LWN: Patch: IDE probe & waiting for busy
		More than that, on typical embedded setups, the kernel may be booted right from flash with almost no firmware work and so will inherit from devices coming right from HW reset.
		- Waiting for busy means we could eventually end up waiting for a crappy command, we shall rather interrupt whatever the drive is doing via a execute diagnostics command.
		My idea here is that in real life, we don't have to deal with the case where the drive is already running some command.
	lwn.net /Articles/10520 (384 words)

	[No title] (Site not responding. Last check: 2007-11-04)
		The answers to assignment number 1 : ------------------------------------ ********* 2.3 ******* With busy waiting**, a process keeps testing for some condition.
		With blocking, a process gives up the CPU and is awakened later when the condition it is waiting for has become true.
		TSL is a busy waiting lock that is normally used for waiting for a very short period of time to enter a short critical section.
	www.cis.syr.edu /courses/CIS657/answers.1 (456 words)

	Excel Pausing or waiting on busy :: MrExcel Message Board
		The problem is that because the system is busy saving the frist work book, when I do the ActiveWindow.Close SaveChanges:=False for the second workbook, I get a Excel has caused an error and needs to shut down.
		I would like to have a way to wait between the two ActiveWindow.Close statements until the the system is no longer busy with the save.
		The "True" portion then tells it to wait until control is returned to Excel before continuing with the macro.
	www.mrexcel.com /archive2/8800/9875.htm (1070 words)

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