Another way of thinking about a commit is who currently owns the definitive version (where all future accesses should have to go through the owner) of the cache line.
apk
Write-back buffer doesn't affect time of commit because the commit was when the processor got the right to bring the value into the M state. The actual complete write (bits are changed in cache/memory) can happen later.
chenboy
write-back buffer doesn't effect time of commit, this is because all processors will check the value in the write-back buffer before they check the memory, so if a processor successfully get to M state then modify a cache line, it will always be observed by other processors.
rrp123
A commit happens when all the processors know that one processor has the cache line in the 'M' state. This happens when the broadcast goes across the bus and all the processors see that message. When the actual write to memory or some other processor happens is irrelevant.
Another way of thinking about a commit is who currently owns the definitive version (where all future accesses should have to go through the owner) of the cache line.
Write-back buffer doesn't affect time of commit because the commit was when the processor got the right to bring the value into the M state. The actual complete write (bits are changed in cache/memory) can happen later.
write-back buffer doesn't effect time of commit, this is because all processors will check the value in the write-back buffer before they check the memory, so if a processor successfully get to M state then modify a cache line, it will always be observed by other processors.
A commit happens when all the processors know that one processor has the cache line in the 'M' state. This happens when the broadcast goes across the bus and all the processors see that message. When the actual write to memory or some other processor happens is irrelevant.