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- We have to be more precise in computer science... - 1 Update
- I think i have made a mistake - 1 Update
- We have to be carrefull - 2 Updates
- In my previous posts about intelligence - 1 Update
- Here is my theory about intelligence - 3 Updates
| Ramine <ramine@1.1>: Dec 08 07:09PM -0800 Hello, We have to be more precise in computer science... To be more sure i have just benchmarked a cache-line transfer between cores and you will not believe it ! it is so expensive on x86 ! cause it takes around 800 CPU cycles , so i think i have correctly reasoned when i have said that the following reader-writer lock (of Joe Duffy an architect at Microsoft) is a garbage. So please reread carefully my reasonning that follows cause it is correct and true: I must say that we have to be carefull, because i have just read the following webpage about a more scalable reader/writer lock by an architect at microsoft called Joe Duffy... but you have to be carefull because this reader/writer lock is not really scalable, it is a garbage, and i will think as an architect and explain to you why... Here is the webpage, and my explanation follows... http://joeduffyblog.com/2009/02/20/a-more-scalable-readerwriter-lock-and-a-bit-less-harsh-consideration-of-the-idea/ So look inside the EnterWriteLock() of the reader/writer above, you will notice that it is first executing Interlocked.Exchange(ref m_writer, 1), that means it is atomicaly making m_writer equal 1, so that to block readers from entering the reader section, but this is garbage, cause look after that he is doing this: for (int i = 0; i < m_readers.Length; i++) while (m_readers[i].m_taken != 0) sw.SpinOnce(); So after making m_writers equal 1 so that to block the readers, he is transfering many cache-lines between cores, and this is really expensive and it will make the serial part of the Amdahl's law bigger and bigger when more and more cores will be used , so this will not scale, so it is garbage. The Dmitry Vyukov distributed reader-writer mutex doesn't have this weakness, because look at the source code here: http://www.1024cores.net/home/lock-free-algorithms/reader-writer-problem/distributed-reader-writer-mutex Because he is doing this on the distr_rw_mutex_wrlock() side: for (i = 0; i != mtx->proc_count; i += 1) pthread_rwlock_wrlock(&mtx->cell[i].mtx); So we have to be smart here and notice with me that as the "i" counter variable goes from 0 to proc_count, the reader side will still be allowed to enter and to enter again the reader section on scenarios with more contention, so in contrast with the above reader-writer lock, this part of the distributed lock is not counted as only a serial part of the Amdahl's law, because it allows also the reader threads to enter and to enter again the reader section, so this part contains a parallel part of the Amdahl's law, and this makes this distributed reader-writer lock to effectively scale. That's even better with my Distributed sequential lock , because it scales even better than the distributed reader-writer mutex of Dmitry Vyukov. Hope you have understood my architect way of thinking. Thank you for your time. Amine Moulay Ramdane. |
| Ramine <ramine@1.1>: Dec 08 05:25PM -0800 Hello, I think i have made a mistake about the follwing reader-writer lock of Joe Duffy: http://joeduffyblog.com/2009/02/20/a-more-scalable-readerwriter-lock-and-a-bit-less-harsh-consideration-of-the-idea/ Since a cache-line transfer between cores is not at all expensive, so the serial part of the Amdahl's law for this reader-writer above will still be smaller with more and more cores, so this will make this reader-writer lock above of Joe Duffy really scalable on read-mostly scenarios. Thank you, Amine Moulay Ramdane. |
| Ramine <ramine@1.1>: Dec 08 03:16PM -0800 Hello, I must say that we have to be carefull, because i have just read the following webpage about a more scalable reader/writer lock by an architect at microsoft called Joe Duffy... but you have to be carefull because this reader/writer lock is not really scalable, it is a garbage, and i will think as an architect and explain to you why... Here is the webpage, and my explanation follows... http://joeduffyblog.com/2009/02/20/a-more-scalable-readerwriter-lock-and-a-bit-less-harsh-consideration-of-the-idea/ So look inside the EnterWriteLock() of the reader/writer above, you will notice that it is first executing Interlocked.Exchange(ref m_writer, 1), that means it is atomicaly making m_writer equal 1, so that to block readers from entering the reader section, but this is garbage, cause look after that he is doing this: for (int i = 0; i < m_readers.Length; i++) while (m_readers[i].m_taken != 0) sw.SpinOnce(); So after making m_writers equal 1 so that to block the readers, he is transfering many cache-lines between cores, and this is really expensive and it will make the serial part of the Amdahl's law bigger and bigger when more and more cores will be used , so this will not scale, so it is garbage. The Dmitry Vyukov distributed reader-writer mutex doesn't have this weakness, because look at the source code here: http://www.1024cores.net/home/lock-free-algorithms/reader-writer-problem/distributed-reader-writer-mutex Because he is doing this on the distr_rw_mutex_wrlock() side: for (i = 0; i != mtx->proc_count; i += 1) pthread_rwlock_wrlock(&mtx->cell[i].mtx); So we have to be smart here and notice with me that as the "i" counter variable goes from 0 to proc_count, the reader side will still be allowed to enter and to enter again the reader section on scenarios with more contention, so in contrast with the above reader-writer lock, this part of the distributed lock is not counted as only a serial part of the Amdahl's law, because it allows also the reader threads to enter and to enter again the reader section, so this part contains a parallel part of the Amdahl's law, tand this makes this distributed reader-writer lock to effectively scale. That's theven better with my Distributed sequential lock , because it scales even better than the distributed reader-writer mutex of Dmitry Vyukov. Hope you have understood my architect way of thinking. Thank you for your time. Amine Moulay Ramdane. |
| Ramine <ramine@1.1>: Dec 08 03:25PM -0800 I correct some typos , please read again... Hello, I must say that we have to be carefull, because i have just read the following webpage about a more scalable reader/writer lock by an architect at microsoft called Joe Duffy... but you have to be carefull because this reader/writer lock is not really scalable, it is a garbage, and i will think as an architect and explain to you why... Here is the webpage, and my explanation follows... http://joeduffyblog.com/2009/02/20/a-more-scalable-readerwriter-lock-and-a-bit-less-harsh-consideration-of-the-idea/ So look inside the EnterWriteLock() of the reader/writer above, you will notice that it is first executing Interlocked.Exchange(ref m_writer, 1), that means it is atomicaly making m_writer equal 1, so that to block readers from entering the reader section, but this is garbage, cause look after that he is doing this: for (int i = 0; i < m_readers.Length; i++) while (m_readers[i].m_taken != 0) sw.SpinOnce(); So after making m_writers equal 1 so that to block the readers, he is transfering many cache-lines between cores, and this is really expensive and it will make the serial part of the Amdahl's law bigger and bigger when more and more cores will be used , so this will not scale, so it is garbage. The Dmitry Vyukov distributed reader-writer mutex doesn't have this weakness, because look at the source code here: http://www.1024cores.net/home/lock-free-algorithms/reader-writer-problem/distributed-reader-writer-mutex Because he is doing this on the distr_rw_mutex_wrlock() side: for (i = 0; i != mtx->proc_count; i += 1) pthread_rwlock_wrlock(&mtx->cell[i].mtx); So we have to be smart here and notice with me that as the "i" counter variable goes from 0 to proc_count, the reader side will still be allowed to enter and to enter again the reader section on scenarios with more contention, so in contrast with the above reader-writer lock, this part of the distributed lock is not counted as only a serial part of the Amdahl's law, because it allows also the reader threads to enter and to enter again the reader section, so this part contains a parallel part of the Amdahl's law, and this makes this distributed reader-writer lock to effectively scale. That's even better with my Distributed sequential lock , because it scales even better than the distributed reader-writer mutex of Dmitry Vyukov. Hope you have understood my architect way of thinking. Thank you for your time. Amine Moulay Ramdane. |
| Ramine <ramine@1.1>: Dec 08 12:13PM -0800 Hello, In my previous posts about intelligence, i was speaking about the "hardware", i mean about the "brain" , so i was speaking about genetics and intelligence, i was not speaking about knowledge. Thank you, Amine Moulay Ramdane. |
| Ramine <ramine@1.1>: Dec 08 10:58AM -0800 Hello, I have thought yesterday about what is intelligence, so here is my theory about intelligence , and i think it is correct... The way the neurals in the brain are interconnected does construct a different kind of architecture in the brain in each person, the way neurals in the brain are interconnected can also make the brain very fast, and can make the searching mechanism of the brain faster than the software or hardware Breadth first search and deep first search , the neurals in the brain are interconnected in a way that can construct more faster architectures in the brain that can use different and faster searching technics than Breadth first search and deep first search ,but they use different ways of interconnecting the neurals of the brain so that the solution of the problem can come very fast, and this is what we call intelligence. But there is a weakness in human, cause i think IQ tests are constituted with a kind of small problems, small in term of "complexity", and because the problems of IQ tests are small in complexity, this permit intelligent human to solve them faster because the way neurals in the brain are interconnected can also make the brain very fast, and can make the searching mechanism of the brain faster than the software or hardware Breadth first search and deep first search , but if you make IQ tests more complex than they are , i don't think intelligent person will succeed there tests with high scores, or if you hide some parts of the problem , this will make the problem hard for an intelligent human to solve it. This is my theory about what is intelligence, and i think it is correct. Thank you, Amine Moulay Ramdane. |
| Ramine <ramine@1.1>: Dec 08 11:55AM -0800 On 12/8/2014 10:59 AM, Ramine wrote: > are interconnected can also make the brain very fast, and can make > the searching mechanism of the brain faster than the software or >hardware Breadth first search and deep first search I have said that IQ tests are small in term of complexity, what i wanted to say is that there complexity is relative to the complexity of all the problems that are found in our universe and found in theory etc.... i don't wanted to say that there complexity is relative to the capacity of the human that want to pass those IQ tests. Hope you have understood. Thank you, Amine Moulay Ramdane. |
| Ramine <ramine@1.1>: Dec 08 12:01PM -0800 Hello, I was speaking about the "hardware", i mean about the "brain" , so i was speaking about genetics and intelligence, i was not speaking about knowledge. Thank you, Amine Moulay Ramdane. |
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