Re: [PATCH] powerpc/book3s64/radix: make tlb_single_page_flush_ceiling a debugfs entry

["Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>]

On 8/12/21 12:58 PM, Michael Ellerman wrote:
> Christophe Leroy <christophe.leroy@csgroup.eu> writes:
>> Le 10/08/2021 à 06:53, Aneesh Kumar K.V a écrit :
>>> Similar to x86/s390 add a debugfs file to tune tlb_single_page_flush_ceiling.
>>>
>>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
>>> ---
>>>    arch/powerpc/mm/book3s64/radix_tlb.c | 48 ++++++++++++++++++++++++++++
>>>    1 file changed, 48 insertions(+)
>>>
>>> diff --git a/arch/powerpc/mm/book3s64/radix_tlb.c b/arch/powerpc/mm/book3s64/radix_tlb.c
>>> index aefc100d79a7..5cca0fe130e7 100644
>>> --- a/arch/powerpc/mm/book3s64/radix_tlb.c
>>> +++ b/arch/powerpc/mm/book3s64/radix_tlb.c
>>> @@ -17,6 +17,7 @@
> ...
>>> +
>>> +static int __init create_tlb_single_page_flush_ceiling(void)
>>> +{
>>> +	debugfs_create_file("tlb_single_page_flush_ceiling", S_IRUSR | S_IWUSR,
>>> +			    powerpc_debugfs_root, NULL, &fops_tlbflush);
>>
>> Could you just use debugfs_create_u32() instead of re-implementing simple read and write ?
> 
> Yeah AFAICS that should work fine.
> 
> It could probably even be a u16?
> 

I was looking at switching all that to u64. Should i fallback to u16, 
considering a tlb_signle_page_flush_ceiling value larger that 2**16 
doesn't make sense?

-aneesh