how does clock control various events(operations) from being occurred in desired sequence?what is the significance of a clock cycle time(i've heard that many operations can be issued in a single clock cycle)?
or simply,how does CPU controls operation ordering?
CPUs have various processing units (float, vector, integer), and pipelines of different lengths for each unit.
The clock determines at which speed it will go through all operations in a pipeline, each operation being a tick. Once it gets to the end, the result is sent back to cache/memory.
Multiple pipelines can be active at the same time.
That's all I can tell you..
Ars Technica used to have great articles about this, such as this one:
The clock does not control the sequence of instructions. The clock controls the amount of times per second that the CPU "ticks." Each time is referred as a cycle and consequently each cycle takes some time to complete.
The sequence of instructions is dictated by the running program. Modern CPUs also include optimisations that influence the exact sequence.
These optimisations also make the clock speed (= amount of cycles per second) less significant. For example a dual core CPU is able to execute two instructions in the same cycle.
Yes usually instructions complete in a couple of cycles and compilers optimise the programs to use costly instructions less.