0 votes 0 votes As write through strategy is mentioned shouldnt we take SIMUALTANEOUS access formula for both read as well as write? when we will use read as parallel access formula? CO and Architecture made-easy-test-series co-and-architecture cache-memory + – Markzuck asked Dec 21, 2018 • edited Mar 3, 2019 by akash.dinkar12 Markzuck 769 views answer comment Share Follow See all 13 Comments See all 13 13 Comments reply arvin commented Dec 21, 2018 reply Follow Share i think if we could have used simuletaneous access for read also... will there be any need for cache memory? no na.. since read needs no modification we will not use simuletaneous access. 0 votes 0 votes Markzuck commented Dec 21, 2018 reply Follow Share ok so read is always Hierarchial? and for write: if write through then parallel write back then hierarchial? 0 votes 0 votes arvin commented Dec 21, 2018 reply Follow Share refer this :https://gateoverflow.in/76502/me-co-write-through 0 votes 0 votes Gokulnath commented Dec 21, 2018 reply Follow Share Write through only means that all the cache accesses also go to the main memory. So even if you have a cache hit or a miss, the access time will be equal to the main memory access time. For a read, we first check the cache. If it is not present, then we go to the main memory. Hence, in case of a miss, the access time is Cache Time + Main Memory time. 1 votes 1 votes Markzuck commented Dec 21, 2018 reply Follow Share yes, so for read always Heirarchial access irrespective of write through or write back? 0 votes 0 votes Gokulnath commented Dec 21, 2018 reply Follow Share Everything is always hierarchical. None of the standard books mention about simultaneous access of cache, it's up to you to decide how the access is done now. I always take everything as hierarchical according to what's given in the books. 0 votes 0 votes Markzuck commented Dec 21, 2018 reply Follow Share here for very same type of question they took ONLY Tm for read miss please tell one concept as its diff everywhere thanks in advance : ) 0 votes 0 votes Markzuck commented Dec 22, 2018 reply Follow Share shall read always be taken as Hierarchial? as everytime only the writing strategy is mentioned. 0 votes 0 votes Gokulnath commented Dec 23, 2018 reply Follow Share Read is always hierarchical. Also, the average they've calculated is incorrect. With 750, 45 has to be added as you'll have to look into the cache before declaring that it is a miss. 2 votes 2 votes Markzuck commented Dec 26, 2018 reply Follow Share thanks @Gokulnath, but could you please help me with this? why simultaneous taken here instead of heirarchial? here: https://gateoverflow.in/118597/gate2017-2-45 0 votes 0 votes Shubhgupta commented Dec 26, 2018 reply Follow Share it's hierarchical only check one more time we always don't consider the hierarchical for read because if question specify something for simultaneous or hierarchical then we consider according to that. If you will notice in first question which you have mentioned in question there is word like "memory hierarchy" so thats why we were using hierarchical access there but in second question its nothing mentioned like so if i go according to all previous year gate question by default we used hierarchical access. Hope this help. 0 votes 0 votes Markzuck commented Dec 28, 2018 reply Follow Share @Shubhgupta yes perfect! so as in 2nd also they didn't mentioned anything so it should have been hierarchial only right? 0 votes 0 votes Arjun commented Dec 28, 2018 reply Follow Share You should buy a candle before taking ME COA tests. 0 votes 0 votes Please log in or register to add a comment.