Is the bulk transfer transferring more than our code has asked for (i.e. transferring 8 bytes when we just need 4 bytes, assuming this extra data will be eventually used when it resides in cache) or is it transferring the bulk of data because the accesses were reordered (bulk of data being transferred is the sum of different bytes from different accesses)?
HingOn
i think its the latter case: multiple small requests are coalesced because they map to the same row in a bank.
Is the bulk transfer transferring more than our code has asked for (i.e. transferring 8 bytes when we just need 4 bytes, assuming this extra data will be eventually used when it resides in cache) or is it transferring the bulk of data because the accesses were reordered (bulk of data being transferred is the sum of different bytes from different accesses)?
i think its the latter case: multiple small requests are coalesced because they map to the same row in a bank.
http://15418.courses.cs.cmu.edu/spring2015/lecture/memory/slide_017
When is this mode used/not used, if the whole cache line needs to be read anyway?
@caretcaret the whole line needs to be loaded into the row buffer, but it need not be read from the row buffer into cache.