1 The Exam

Exam 3 was given in class on Thursday 2 May, 2019. The PDF of the exam is available here. You can find your individual responses on the submission page.

Stat	Exam 1	Exam 2	Exam 3
High	91.1%	93.1%	98.2%
Median	80.6%	77.8%	85.3%
Mean	78.6%	76.0%	85.0%
Low	54.8%	52.2%	60.1%
StdDev	9.6%	11.3%	8.7%

A few notes that may not be evident from the uploads:

• Q23 and Q24 had a lot of conceptual overlap, and were weighted half as much as other questions, though you’ll see a normalized (out of 1) score displayed if you missed points on it.
• Q15 I dropped as ambiguous

2 Key

Question	Key
Q1	2
Q2.1	True
Q2.2	True
Q3	1
Q4	2
Q5	3
Q6	20,007
Q7	5
Q8	1
Q9	3 (1 also accepted)
Q10	5
Q11	1
Q12	Two deadlocks: a locked barrier (so either remove 1 and 3 or remove 2) and a barrier some threads run more often than others (so remove 4)
Q13	1
Q14	4
Q15	(dropped)
Q16.1	False
Q16.2	True
Q16.3	True
Q16.4	True – a non-signaling page-fault is handled by mapping a new page
Q16.5	True – new page access = new TLB entry
Q16.6	True – page faults are caused by memory accesses
Q17.1	True
Q17.2	True
Q17.3	True
Q17.4	True
Q17.5	True
Q17.6	False
Q18	1 – TLBs cache VA→PA mappings, not page tables, and only one new mapping here
Q19.1	False
Q19.2	True
Q19.3	True
Q19.4	True
Q19.5	False – this would work for Specter, but not Meltdown
Q20	29 = 512
Q21	58 – 2 more bits per VPN and 2 more for the PO too
Q22	4
Q23.1	True
Q23.2	True
Q23.3	False
Q23.4	True
Q24.1	False
Q24.2	False
Q24.3	True
Q24.4	False
Q25	512KB
Q26	3 (5 also accepted)
Q27.1	True
Q27.2	False
Q27.3	True
Q27.4	False
Q28.1	False
Q28.2	True
Q28.3	False
Q28.4	True
Q29.1	True
Q29.2	True
Q29.3	True
Q29.4	True
Q29.5	True – cannot have cycles without this
Q29.6	True – cannot have cycles without this
Q30.1	True
Q30.2	True
Q30.3	False
Q30.4	False – user account changes require kernel mode, meaning an exception
Q30.5	False
Q30.6	False
Q31.1	False
Q31.2	False
Q31.3	False
Q31.4	True
Q32	3