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"Working set is a concept in computer science which defines the amount of memory that a process requires in a given time interval. Definition Peter Denning (1968) defines "the working set of information W(t, \tau) of a process at time t to be the collection of information referenced by the process during the process time interval (t - \tau, t)". Typically the units of information in question are considered to be memory pages. This is suggested to be an approximation of the set of pages that the process will access in the future (say during the next \tau time units), and more specifically is suggested to be an indication of what pages ought to be kept in main memory to allow most progress to be made in the execution of that process. Rationale The effect of the choice of what pages to be kept in main memory (as distinct from being paged out to auxiliary storage) is important: if too many pages of a process are kept in main memory, then fewer other processes can be ready at any one time. If too few pages of a process are kept in main memory, then its page fault frequency is greatly increased and the number of active (non-suspended) processes currently executing in the system approaches zero. The working set model states that a process can be in RAM if and only if all of the pages that it is currently using (often approximated by the most recently used pages) can be in RAM. The model is an all or nothing model, meaning if the pages it needs to use increases, and there is no room in RAM, the process is swapped out of memory to free the memory for other processes to use. Often a heavily loaded computer has so many processes queued up that, if all the processes were allowed to run for one scheduling time slice, they would refer to more pages than there is RAM, causing the computer to "thrash". By swapping some processes from memory, the result is that processes—even processes that were temporarily removed from memory—finish much sooner than they would if the computer attempted to run them all at once. The processes also finish much sooner than they would if the computer only ran one process at a time to completion since it allows other processes to run and make progress during times that one process is waiting on the hard drive or some other global resource. In other words, the working set strategy prevents thrashing while keeping the degree of multiprogramming as high as possible. Thus it optimizes CPU utilization and throughput. Implementation The main hurdle in implementing the working set model is keeping track of the working set. The working set window is a moving window. At each memory reference a new reference appears at one end and the oldest reference drops off the other end. A page is in the working set if it is referenced in the working set window. To avoid the overhead of keeping a list of the last k referenced pages, the working set is often implemented by keeping track of the time t of the last reference, and considering the working set to be all pages referenced within a certain period of time. The working set isn't a page replacement algorithm, but page-replacement algorithms can be designed to only remove pages that aren't in the working set for a particular process. One example is a modified version of the clock algorithm called WSClock. Variants Working set can be divided into code working set and data working set. This distinction is important when code and data are separate at the relevant level of the memory hierarchy, as if either working set does not fit in that level of the hierarchy, thrashing will occur. In addition to the code and data themselves, on systems with virtual memory, the memory map (of virtual memory to physical memory) entries of the pages of the working set must be cached in the translation lookaside buffer (TLB) for the process to progress efficiently. This distinction exists because code and data are cached in small blocks (cache lines), not entire pages, but address lookup is done at the page level. Thus even if the code and data working sets fit into cache, if the working sets are split across many pages, the virtual address working set may not fit into TLB, causing TLB thrashing. Analogs of working set exist for other limited resources, most significantly processes. If a set of processes requires frequent interaction between multiple processes, then it has a ' that must be coscheduled in order to progress: If the processes are not scheduled simultaneously – for example, if there are two processes but only one core on which to execute them – then the processes can only advance at the rate of one interaction per time slice. Other resources include file handles or network sockets – for example, copying one file to another is most simply done with two file handles: one for input, one for output, and thus has a "file handle working set" size of two. If only one file handle is available, copying can still be done, but requires acquiring a file handle for the input, reading from it (say into a buffer), releasing it, then acquiring a file handle for the output, writing to it, releasing it, then acquiring the input file handle again and repeating. Similarly a server may require many sockets, and if it is limited would need to repeatedly release and re-acquire sockets. Rather than thrashing, these resources are typically required for the program, and if it cannot acquire enough resources, it simply fails. See also *Locality of reference *Resident set size *Working set size References *Tanenbaum, Andrew (2009). Modern Operating Systems Third Edition. pp. 209–210 *Denning, P.J. (1980). Working Sets Past and Present. IEEE Transactions on Software Engineering, 1/1980, Volume SE-6, pp. 64–84. *Silberschatz, A., Galvin, P.B., & Gagne, G. (2005). Operating System Concepts, 7th edition. Palatino: Wiley. pp. 346. Category:Operating system technology Category:Virtual memory "
"Enguerrand II (d. 25 October 1053) was the son of Hugh II count of Ponthieu. He assumed the county upon the death of his father on November 20, 1052. Life Enguerrand II was the eldest son and heir of Hugh II, Count of Ponthieu and his wife Bertha of Aumale, heiress of Aumale.Detlev Schwennicke, Europäische Stammtafeln: Stammtafeln zur Geschichte der Europäischen Staaten, Neue Folge, Band III Teilband 4 (Verlag von J. A. Stargardt, Marburg, Germany, 1989), Tafel 635 Enguerrand was married to Adelaide, daughter of Robert I, Duke of Normandy and sister of William the Conqueror. George Edward Cokayne, The Complete Peerage of England Scotland Ireland Great Britain and the United Kingdom, Extant Extinct or Dormant, ed. Vicary Gibbs, Vol. I (The St. Catherine Press, Ltd., London, 1910), pp. 350-2 But at the Council of Reims in 1049, when the proposed marriage of Duke William with Matilda of Flanders was prohibited based on consanguinity, so was Enguerrand's existing marriage to Adelaide, causing him to be excommunicated. Kathleen Thompson, 'Being the Ducal Sister: The Role of Adelaide of Aumale', Normandy and its Neighbours 900-1250; Essays for David Bates, ed. David Crouch, Kathleen Thompson (Brepols Publishers, Belgium, 2011), p. 68 The marriage was apparently annulled c.1049/50.Kathleen Thompson, 'Being the Ducal Sister: The Role of Adelaide of Aumale', Normandy and its Neighbours 900-1250; Essays for David Bates, ed. David Crouch, Kathleen Thompson (Brepols Publishers, Belgium, 2011), p. 71 He had given her in dower, Aumale, which she retained after the dissolution of their marriage.Collectanea topographica et genealogica, Volume 6, ed. Frederic Madden, Bulkeley Bandinel, John G. Nichols (John B. Nichols & Sons, London, 1840), p. 265 The Conqueror's uncle, William of Arques, who had originally challenged Duke William's right to the duchy based on his illegitimacy, had been given the county of Talou by Duke William as a fief, but still defiant and on his own authority proceeded to build a strong castle at Arques.Elisabeth Van Houts, The Normans in Europe (Manchester University Press, Manchester & New York, 2000), p. 68 Enguerrand was allied to William of Arques by virtue of the latter being married to Enguerrand's sister. By 1053 William of Arques was in open revolt against Duke William and Henry I of France came to William of Arques' aid invading Normandy and attempting to relieve the castle of Arques.Jim Bradbury, The Routledge Companion to Medieval Warfare (Routledge, NY, 2004), pp. 160-1 Duke William had put Arques under siege, but had remained mobile with another force in the countryside nearby.David C. Douglas, William the Conqueror (University of California Press, Berkeley and Los Angeles, 1964), p. 388 To relieve the siege Enguerrand was with Henry I of France and on October 25, 1053 was killed when the Normans feigned a retreat in which Enguerrand and his companions followed and were ambushed, a tactic the Normans used again to great success at the Battle of Hastings. Issue Enguerrand married Adelaide of Normandy, Countess of Aumale, daughter of Robert I, Duke of Normandy.The name of Adelaide's mother remains unsettled. David C. Douglas [William the Conqueror, 1964, pp. 381] stated that William had a sister or half-sister Adelaide; that she may have been the daughter of Robert I by a mistress other than Herleva, but that "it is more probable she was the Conqueror's sister of the whole blood". As such the question remains open.George Andrews Moriarty, The Plantagenet Ancestry of King Edward III and Queen Philippa (Mormon Pioneer Genealogy Society, Salt Lake City, UT, 1985), p. 13 By her he had a daughter: * Adelaide, living in 1096.George Edward Cokayne, The Complete Peerage of England Scotland Ireland Great Britain and the United Kingdom, Extant Extinct or Dormant, ed. Vicary Gibbs, Vol. I (The St. Catherine Press, Ltd., London, 1910), p. 351 As Enguerrand died without male issue he was followed by his brother Guy I as Count of Ponthieu.Thomas Stapleton, 'Observations on the History of Adeliza, Sister of William the Conqueror', Archaeologia, Vol. 26 (J.B. Nichols & Sons, 1836), pp. 349-360 References Notes Category:Year of birth unknown Category:Counts of Ponthieu Category:People excommunicated by the Catholic Church Category:1053 deaths Category:11th-century French people "
"Guinea pepper is a name for several unrelated pepper-like spices traded from the general region of West Africa: * Aframomum melegueta from the ginger family (Zingiberaceae), also known as grains of paradise, melegueta pepper, alligator pepper, Guinea grains, ossame, ‘‘ataré’’in Yoruba land, fom wisa, and (ambiguously) Guinea pepper * Piper guineense from the pepper family (Piperaceae), also known as West African pepper, Ashanti pepper, Benin pepper, false cubeb, Guinea cubeb, kale, kukauabe, masoro, sasema, soro wisa, and uziza * Grains of Selim, also known as Kani pepper, Senegal pepper, Ethiopian pepper, Moor pepper, Negro pepper, , , , , , , kimba, kili, and (ambiguously) Guinea pepper ** Xylopia aethiopica from the custard apple family (Annonaceae), primary source of the spice most commonly known in the West as grains of Selim ** Xylopia striata, a closely related source of grains of Selim, with larger seed pods "