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Consider process P that owns 10 physical frames. Suppose process P calls fork() and creates a child process Q.
How many physical frames does the child initially own, without copy-on-write? 10
How many frames does the child initially own, with copy-on-write? 0 not sure if this is a correct answer.
Thank you!
The forked process needs act as if it was an exact image of the parent, so without COW it would indeed own 10 frames initially.
But it can't initially own no memory of its own at all - at least one non-shared frame is necessary: fork doesn't return the same value in the parent and the child, so the page where that return value is stored cannot be shared.
In practice, there will probably be a few pages that aren't shared, the exact number will probably depend on the operating system. The only certain thing is that it can't be zero.
