If either PAE and PSE are active, different paging level schemes are used:
- no PAE and no PSE:
10 | 10 | 12 - no PAE and PSE:
10 | 22.22 is the offset within the 4Mb page, since 22 bits address 4Mb. - PAE and no PSE:
2 | 9 | 9 | 12The design reason why 9 is used twice instead of 10 is that now entries cannot fit anymore into 32 bits, which were all filled up by 20 address bits and 12 meaningful or reserved flag bits.The reason is that 20 bits are not enough anymore to represent the address of page tables: 24 bits are now needed because of the 4 extra wires added to the processor.Therefore, the designers decided to increase entry size to 64 bits, and to make them fit into a single page table it is necessary reduce the number of entries to 2^9 instead of 2^10. - PAE and PSE:
2 | 9 | 21
The Translation Lookahead Buffer (TLB) is a cache for paging addresses.
The Linux kernel makes extensive usage of the paging features of x86 to allow fast process switches with small data fragmentation.
There are also however some features that the Linux kernel might not use, either because they are only for backwards compatibility, or because the Linux devs didn't feel it was worth it yet.
Paging is done by the Memory Management Unit (MMU) part of the CPU.
It was later integrated into the CPU, but the term MMU still used.
Two level address translation to make OS emulation more efficient.
Peter Cordes mentions that some architectures like MIPS leave paging almost completely in the hands of software: a TLB miss runs an OS-supplied function to walk the page tables, and insert the new mapping into the TLB. In such architectures, the OS can use whatever data structure it wants.
Free:
- rutgers-pxk-416 chapter "Memory management: lecture notes"
It is mindblowing that the sale wasn't cancelled due to anti trust.
The outcome of this is that WhatApp will remain with the same feature set forever, while other competitors have been growing, notably Discord and Slack.
It seems that there is a case looming 10 years after the fact: www.cityam.com/facebook-fails-to-block-antitrust-lawsuit-over-whatsapp-and-instagram-ownership/ Wake up???
This means that all secret services in the world have alrady scraped this information for everyone that uses WhatsApp!!!
They just have to go incrementally through the list of all phone numbers... 001 0000 0000, 001 0000 0001, 001 0000 0002, etc. and then you can deduce who has which phone number.
OMG... it is analogous to the Facebook profile face dump.
Sure, it is forbidden in theory: faq.whatsapp.com/general/security-and-privacy/about-harvesting-personal-information/.
It is quite mind blowing that this is polyphyletic on mammals and birds, what can't parallel evolution achieve??
Phylogenetic tree of the vertebrates
. Source. Highlights how birds should obviously be classified as reptiles.
- byjus.com/neet-questions/why-does-dna-contain-thymine-and-rna-uracil says Uracil cannot be repaired by DNA repair mechanisms. But it is also requires less energy to synthesize with.
As of 2022:
- www.ox.ac.uk/students/fees-funding/fees/rates gives study fees. Almost all courses are about 9k pounds / academic year. Courses take minimum 3 years, with an optional 4th year masters. The costs of masters can be higher however, though most aren't much.It is funny to note how Public Policy is comically priced at 45,890 for a course without laboratories, how can a country be so corrupt? :-) It was later brought to Ciro's attention that the reason is that those courses are not usually paid by individuals, but by their employers...Another eye popping one is Mathematical & Computational Finance MSc for £36,370.
- www.ox.ac.uk/students/fees-funding/living-costs gives living costs, an average 12k for the usual 9 month period
- there is the Crankstart scholarship: www.ox.ac.uk/admissions/undergraduate/student-life/help-with-the-cost/crankstart-scholarships which gives 5k/year to students whose families have less than 27k/year income, and values decrease from there to 60k/year income where they become zero.It is funny to note that the scholarship was previously named after a Welsh billionaire who studied there and donated and his wife, Michael Moritz and wife Harriet Heyman. It is actually the Welsh who are creating those scholarships for the English! It is so funny to see. His background is quite amazing, from historian to journalist to venture capitalist.It was later renamed Crankstart after the Crankstart Foundation, presumably to help gather funds from others, but it is just still led by Michael.It does appear that most/all of the natural sciences ones are reasonably priced, perhaps they are subsided.
The median household income at the time was 31k[ref]. Clearly, putting one child through university with that income would be basically impossible, you would pay 19 - 5 = 14k/year, almost half of your income. Two children would be impossible. Remember how each family needs to have two children minimum to perpetuate life?
- cherwell.org/2023/10/02/27000-for-a-library-card/ £27,000 for a library card? published on the Cherwell
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