Thursday, July 5, 2012

ARM, Supercomputing and Power Consumption

Recently folks at MIT demonstrated a 96 core ARM cluster which runs entirely on solar energy[1]. The total power consumption of the entire cluster was around 200 watts.

Detailed figures about the performance are yet to come. I am particularly interested to find out how the system scales in terms of FLOPs/Watt.

I don't know whether the word "weak scaling" is right to use here or not, in my view the idea is the same, i.e if on one machine or core the system achieves x flops per watt will it retain that number if more machines or cores are added? That is to say x flops per watt using two cores or 96 cores etc. Now that's an ideal case to retain the same performance of previous configuration while adding more resources. It will decrease but how much? And especially keeping in mind the kind of workloads.

I am trying to make some educated guesses based on a prior experience with such kind of configuration[2]. I will share them here as I finish .... But for the moment those two articles in the reference section are a must read.

ref:
[1] Building A 96-Core Ubuntu ARM Solar-Powered Cluster 
[2] 12-Core ARM Cluster Benchmarked Against Intel Atom, Ivy Bridge, AMD Fusion http://www.phoronix.com/scan.php?page=article&item=phoronix_effimass_cluster&num=1

Tuesday, November 23, 2010

CHAPTER V.*

There has been an occasional mention in some places above, of the tribe of Súmrahs, and their probable origin from the town of Sámrah, from which place they are said to have emigrated to Sind in the fourth century of the Hijrah or tenth of the christian era, in the days of Khalífah Mamún Abbásì, along with the children of Tamím, who subsequently took the name of Thahím for their tribe. It has been calculated by some historians that their ascendancy dates from that time, continues to their fall at the hands of Sammahs, as will be described in the next chapter, and extends over a period of 505 years, in which are included the periods of the lieutenancy of agents of Ghazní and Ghór dynasties of kings.

It has been mentioned in a previous chapter that in the year 720 A.H. (1320 A.D.), Ghází Malak took the army of Sind and Multán to Dehlí, dethroned Khusró Khán the last of the Ghazní kings and proclaimed himself the king of Dehlí, with the title of Ghayásuddín Taghlak Sháh. About that time, a large number of the Súmrah tribe assembled in the vicinity of Tharrí and taking a man by name Súmrah, as their leader, proclaimed him to be an independent chief of their tribe and country. With their assistance Súmrah soon secured a firm grasp of his princi­pality and cleared the surrounding country of rebellious people. He then managed to marry a daughter of a big zamindár of the place. Her name was Sád. He got a son by her and he named him Bhúngar. At the death of Súmrah, Bhúngar succeeded him as the chief of his tribe. Bhúngar was again succeeded by his son Dódá, who extended his rule to Nasarpúr. After a successful reign, he died leaving a grown up daughter by name Tárí and a minor son by name Sanghár. For the time Tárí took the reins of Government. When Sanghár reached the age of maturity, he replaced his sister on the throne. This young chief made some invasions in the direction of Kachh and brought the country up to Nánaknai* into his possession. At his death, as he had no issue, his widow Hímú, who was ruling in the fort of Adak managed to put her own brothers in possession of the towns of Muhammad Tùr and Tharrí.

About this period, the Súmrah chief Dódá was ruling his people at the castle of Dahkah. Considering the opportunity very favourable, he collected his kinsmen and caste-fellows, invaded the country of Hímú’s brothers, and defeated and killed them. But soon afterwards, one Dádú Phattú, of the descendants of Dódá collected a large number of men and made himself the master of his fore­father’s country. After a quiet reign of some years he died and was succeeded by a chief named Khairá. After Khairá, one Armel became the ruler of the place. As he was a cruel-hearted person and treated his people very badly, some people of the tribe of Sammahs with Unar at their head, revolted against him and killed him in conspiracy with his ministers. The head of Armel was hung on the top of the gate of the fort and Unar was proclaimed their ruler. This occurred in 752 A.H (1351 A.D.). Thus the Govern­ment of Sind passed away from the hands of Súmrahs to those of Sammahs. According to the Muntakhib Tawá­ríkh it was in 445 A.H. (1053 A.D.) that in the reign of Abdurrashíd son of Sultán Mahmúd of Ghazní, who was a weak prince, that the Súmrahs secured their independence and elected Súmrah as their chief. He was suc­ceeded by a line of chiefs that are given below:—



A.H. A.D.
1. Súmrah died 446 = 1054
2. Bhúngar bin Súmrah died 461 = 1068 (After a reign of 15 years)
3. Dódá bin Bhúngar died 485 = 1092 (24 years.)
4. Sanghár died 500 = 1106 (15 years.)
5. Khafíf died 536 = 1141 (36 years.)
6. Umar died 576 = 1180 (40 years.)
7. Dódá died 590 = 1193 (14 years.)
8. Punhún died 623 = 1226 (33 years.)
9. Khinrah died 639 = 1241 (16 years.)
10. Muhammad Túr died 654 = 1256 (15 years.)
11. Khinrah died 658 = 1259 (4 years.)
12. Táí died 682 = 1283 (24 years.)
13. Chanesar died 700 = 1300 (18 years.)
14. Bhúngar died 715 = 1315 (15 years.)
15. Khafíf died 733 = 1332 (18 years.)
16. Dódá died 758 = 1356 (25 years.)
17. Umar died 793 = 1390 (35 years.)
18. Bhúngar died 803 = 1400 (10 years.)
19. Hamír (dethroned by Sammahs.)

Some other stories are related about the causes which led to the downfall of the Súmrah government in Sind. Umar Súmrah, founder of Umarkót, was the last chief but two of this line. He was guilty of two acts of misconduct that greatly exasperated the people and turned their feelings against him. One was his taking away by force a young and beautiful girl, by name Máruí, of the tribe of Márús, residents of the sandhills of Thar, who had already been betrothed to a kinsman of hers.* The other is a similar misconduct on the part of Umar with respect to a girl, by name Gangá, * of the tribe of Tamímís, who too had been previously engaged to a kinsman, who was one of the courtiers of Umar. * The injured relations of these girls are said to have taken their complaints to Sultán Aláuddín of Dehlí, who became very angry with Umar and took steps to remove him from his high position.

Hamír Súmrah, the last ruler, was a very cruel man. His behaviour was perhaps worse than his predecessors. Ráná Mendrah was his wazír. The love of the king and his wazir for the princess Múmal of the tribe of Gujar and the disagreement between them on this account is well known in Sind. * It took place about the close of the reign of the Sùmrahs, and that, with some other events of the like nature, tended towards the downfall of their kingdom.

Chanesar (No. 13) was another of the last batch of Súmrah princes, whose misconduct with the beautiful princess Lílá, a daughter of ráná Khangár, who had been betrothed to her own cousin, formed a factor in the decline *of that dynasty.||

It was also in the reign of one of these Súmrah princes that Dalúrái, a descendant of the Hindú king of the same name, who was the founder of Dalúr or Alór, imitated the ruling Súmrah princes of his own time in immoral behaviour by attempting to seize Badíul Jamál the beloved wife of Saiful Mulúk, a princely merchant travelling through his city and brought down the wrath of God that reduced the ancient towns of Alór and Bhanbrá (or Brahmanábád) to ruins

Chhattah Amrání, a brother of Dalúráí, being offended with him for his misdemeanour came to Baghdád, took 100 Arabs of Sámrah under the leadership of Sayyed Alí Músawí, and came to Sind. After his arrival, his brother Dalúrái submitted to the Sayyed and gave him the hand of his daughter. The Sayyed preferred his residence at Lakallawí (Lakí) and his descendants are the Sayyeds of the place, still in existence. Sometimes this event is considered to be the origin of Súmrahs in Sind. Among other things some bad customs and habits of the people of that age also conduced in a measure to the loss of high position by the Súmrah chiefs of Sind. It is said that these chiefs used to brand their other relations and ordi­nary people’s persons with a mark to show that they were all inferior to them. They themselves used to wear turbans, while they permitted the others only to use the warp of the web or half woven cloth instead; for the sake of distinction. They likewise required the other people to cut off the nails of their hands and feet from their roots. They used clothes on their persons once only and did not get them washed to use them again. On the same principle, perhaps, they never approached women who had once given birth to a child and who therefore were obliged to lead a miserable life. Once it is said that a wise lady got her husband’s sheets that he had thrown aside, washed by a washerman and kept the same scented with a sweet scent. When her husband required new sheets after a bath, the lady gave him the washed ones. The man was so much struck with the cleanness and softness of the clothes that he enquired from his wife as to how she had managed to get them for him. The wife then informed him that they were the same old dirty clothes that he had thrown away. She then showed to him the folly of the men in not using certain things that could still be very useful after some manipulation. Next she slowly explained to him the application of the same rule to women, who had been thrown aside, after giving birth to a child. By degrees these bad customs were given up by the people.

It is said that the Súmrahs were in the habit of drink­ing liquor and eating the flesh of buffaloes. One day some Súmrahs took away a young buffalo from the house of some Sammah in his absence. When the man returned home, his wife complained to him of what had happened and reproached him saying “To-day these Súmrahs have forcibily taken away a young buffalo from your houses, tomorrow they will take away your females.” The man was much ashamed. He took the complaint before the heads of his tribe, collected a large gathering of men, killed some chief men of the Súmrahs and left the town.

In short the Sammahs were very much ill-treated by the Súmrahs, who were the ruling class. They therefore made common cause and left Sind in a body and went to Kachh. The ruler of Kachh treated them kindly and at their request gave them a large tract of land for cultivation. In return the Sammahs were to give 500 cart-loads of grass annually, when the crops were raised. This annual assessment they continued giving for some years, during which time they learnt the ways of govern­ment and felt themselves strong enough to overpower an enemy. Then they began to lay a plot to seize the castle.

It is said that a Brahmin was posted at the gate of the castle and as he was an astrologer too he had the privilege of permitting men to enter or preventing them from entering the walls of the castle. Once upon a time, after the harvest was over, when these Sammahs brought the 500 carts of grass in the usual way, they concealed two brave armed men in each cart, in the midst of the grass. As the carts were admitted into the castle by the gate­keepers to deposit the hay in the appointed place, the Brahmin is said to have observed that he smelt or perceived raw flesh in the grass. But the door-keepers only laughed at the idea. However, as the Brahmin must not be disbelieved, some men thrust lances into some grass loads to test them. They say that the blades of the lances pierced the bodies of the men concealed in the grass and as they came out of their bodies they had courage enough to wipe them with their clothes and to send them out clean of their blood. This removed all suspicion and all the carts were allowed to go in. During the next night, when all was silent in the castle, the armed men rushed out, stopped the gates, called their comrades outside the castle who were on the alert to join them, killed the ruler of Kachh and other occupants of the place and took possession of the fort. Since that time these Sammahs and their descendants have been a ruling class in Kachh.

It has been said above that complaints were taken to Sultán Aláuddín of Dehlí against the Súmrahs and he was induced to invade their country and punish them for their cruelties. Accordingly Sultán Aláuddín or his general Sálár Khán came to Sind with an army. The Súmrahs prepared to sell their lives very dear. At the suggestion of a party of Chárans (or bards) who enjoyed respect and confidence of both the tribes, the Sùmrahs sent up their women and children to Kachh under the protection of Abrah Sammah the chief of the Sammahs in that part of the country and themselves lay in wait to fight with the Sultán’s army. Sapar Súmrah was then the headman of the Súmrah tribe. Under his command therefore the Súmrahs arranged themselves for a battle. But they were soon defeated and driven out and their leader was killed. They were therefore obliged to leave their chief town of Muhammad Túr and go to Kachh, whither they had already sent their families. But in that they had reckoned without their host. For, as soon as their familes arrived in Kachh, Abrah Sammah caught them in a trap and fell upon them in a murderous manner. On their flight to Kachh, the men themselves were pur­sued by their enemy, the Sultán’s army, who only joined the Sammahs of the place in attacking them. The Súmrahs did sell their lives very dear, for they died while fighting, with the exception of a few men who escaped.

During this confusion it is said that a few young virgins of the Súmrah tribe fell into the hands of the Sultán’s army. Being hard pressed by them and deter­mined to save their chastity, they prayed to God, and the ground under them immediately cracked and engulphed them. The spot is still visited by people, who are shown remnants of their veils that are believed to have been left behind as dumb witnesses of their disappearance.

In short, the tribe of Súmrahs was thus extirpated from Sind and their chief town of Muhammad Túr made desolate by the plunderous hands of the army of the Sultán of Dehlí. The Sammahs who succeeded the Súmrahs built new towns near it, viz:—Sámuí and others, and considered the old site of Muhammad Túr, which was situated in the parganah of Darak as a cursed and an unlucky spot.