On 07/08/2015 19:03, Alvise Rigo wrote:
> +static inline int cpu_physical_memory_excl_atleast_one_clean(ram_addr_t addr)
> +{
> + unsigned long *bitmap = ram_list.dirty_memory[DIRTY_MEMORY_EXCLUSIVE];
> + unsigned long next, end;
> +
> + if (likely(smp_cpus <= BITS_PER_LONG)) {
This only works if smp_cpus divides BITS_PER_LONG, i.e. BITS_PER_LONG %
smp_cpus == 0.
> + unsigned long mask = (1 << smp_cpus) - 1;
> +
> + return
> + (mask & (bitmap[BIT_WORD(EXCL_BITMAP_GET_OFFSET(addr))] >>
> + (EXCL_BITMAP_GET_OFFSET(addr) & (BITS_PER_LONG-1)))) != mask;
> + }
> +
> + end = BIT_WORD(EXCL_BITMAP_GET_OFFSET(addr)) + smp_cpus;
> + next = find_next_zero_bit(bitmap, end,
> + BIT_WORD(EXCL_BITMAP_GET_OFFSET(addr)));
> +
> + return next < end;
> +static inline int cpu_physical_memory_excl_is_dirty(ram_addr_t addr,
> + unsigned long cpu)
> +{
> + unsigned long *bitmap = ram_list.dirty_memory[DIRTY_MEMORY_EXCLUSIVE];
> + unsigned long end, next;
> + uint32_t add;
> +
> + assert(cpu <= smp_cpus);
> +
> + if (likely(smp_cpus <= BITS_PER_LONG)) {
> + cpu = (cpu == smp_cpus) ? (1 << cpu) - 1 : (1 << cpu);
> +
> + return cpu & (bitmap[BIT_WORD(EXCL_BITMAP_GET_OFFSET(addr))] >>
> + (EXCL_BITMAP_GET_OFFSET(addr) & (BITS_PER_LONG-1)));
> + }
> +
> + add = (cpu == smp_cpus) ? 0 : 1;
Why not have a separate function for the cpu == smp_cpus case?
I don't think real hardware has ll/sc per CPU. Can we have the bitmap as:
- 0 if one or more CPUs have the address set to exclusive, _and_ no CPU
has done a concurrent access
- 1 if no CPUs have the address set to exclusive, _or_ one CPU has done
a concurrent access.
Then:
- ll sets the bit to 0, and requests a flush if it was 1
- when setting a TLB entry, set it to TLB_EXCL if the bitmap has 0
- in the TLB_EXCL slow path, set the bit to 1 and, for conditional
stores, succeed if the bit was 0
- when removing an exclusive entry, set the bit to 1
Paolo
