Re: Excessive TLB flush ranges

Thomas Gleixner
2023-05-16T08:21:00Z

On Tue, May 16 2023 at 10:18, Thomas Gleixner wrote:

> On Tue, May 16 2023 at 08:37, Thomas Gleixner wrote:
>> On Mon, May 15 2023 at 22:31, Russell King wrote:
>>>> + list_for_each_entry(va, list, list) {
>>>> + /* flush range by one by one 'invlpg' */
>>>> + for (addr = va->va_start; addr < va->va_end; addr += PAGE_SIZE)
>>>> + flush_tlb_one_kernel(addr);
>>>
>>> Isn't this just the same as:
>>> flush_tlb_kernel_range(va->va_start, va->va_end);
>>
>> Indeed.
>
> Actually not. At least not on x86 where it'd end up with 3 IPIs for that
> case again, instead of having one which walks the list on each CPU.

ARM32 has the same problem when tlb_ops_need_broadcast() is true.

Thanks,

tglx