multithreading - How does RAM is shared in multi core environment? -

i learnt multi core processors have more 1 processing units( i.e. main executing units alu etc.) , better @ performance. want know how share physical memory. i'll take following example make question clearer - say, there memory location m in physical memory , 2 threads t1 , t2 running on different cores. possible t1 , t2 access m @ same instance of time or have wait 1 other complete access i.e. share same memory bus have wait, 1 or can read m @ same instance of time 2 different memory buses? if former case, there not performance gain right, have wait memory bus free?

• summarising, memory operations independent of other cores or each core can make physical memory access when memory bus free?

memory access depends on ram module , not on cpu , cpu cores can request access access given first , depends on ram itself!