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

On 8/12/21 12:58 PM, Michael Ellerman wrote:

Christophe Leroy [off-list ref] writes:

quoted

Le 10/08/2021 à 06:53, Aneesh Kumar K.V a écrit :

quoted

Similar to x86/s390 add a debugfs file to tune tlb_single_page_flush_ceiling.

Signed-off-by: Aneesh Kumar K.V <redacted>
---
   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 @@

...

quoted

quoted

+
+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