[PATCH] powerpc/pseries: Provide verbose info about HPT resizing attempt

[PATCH] powerpc/pseries: Provide verbose info about HPT resizing attempt

[Bharata B Rao]

When HPT resizing is attempted in response to memory hotplug, we see
the following messages from the kernel:

lpar: Attempting to resize HPT to shift 23
Unable to resize hash page table to target order 23: -28

This gives a feeling as though we are trying to grow HPT but failed and
hence bad things might happen in future. Improve the message a bit
by explicitly printing the existing HPT shift value in addtion to
the newly targeted value so that it is clear that we haven't failed
to grow HPT. After this commit, the same message will appear like this:

lpar: Attempting to resize HPT from shift 25 to 23
Unable to resize hash page table to target order 23: -28

Signed-off-by: Bharata B Rao <bharata@linux.ibm.com>
---
 arch/powerpc/platforms/pseries/lpar.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index f2a9f0adc2d3..ecc7fa1876a9 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -875,7 +875,8 @@ static int pseries_lpar_resize_hpt(unsigned long shift)
 	if (!firmware_has_feature(FW_FEATURE_HPT_RESIZE))
 		return -ENODEV;
 
-	pr_info("Attempting to resize HPT to shift %lu\n", shift);
+	pr_info("Attempting to resize HPT from shift %llu to %lu\n", ppc64_pft_size,
+		shift);
 
 	t0 = ktime_get();
 
-- 
2.17.1

Re: [PATCH] powerpc/pseries: Provide verbose info about HPT resizing attempt

[Bharata B Rao]

On Wed, Apr 10, 2019 at 08:20:53PM +1000, Michael Ellerman wrote:
> Bharata B Rao <bharata@linux.ibm.com> writes:
> 
> > When HPT resizing is attempted in response to memory hotplug, we see
> > the following messages from the kernel:
> >
> > lpar: Attempting to resize HPT to shift 23
> > Unable to resize hash page table to target order 23: -28
> >
> > This gives a feeling as though we are trying to grow HPT but failed and
> > hence bad things might happen in future. Improve the message a bit
> > by explicitly printing the existing HPT shift value in addtion to
> > the newly targeted value so that it is clear that we haven't failed
> > to grow HPT. After this commit, the same message will appear like this:
> >
> > lpar: Attempting to resize HPT from shift 25 to 23
> > Unable to resize hash page table to target order 23: -28
> >
> > Signed-off-by: Bharata B Rao <bharata@linux.ibm.com>
> 
> I'd be inclined to just remove the "Attempting .." message.
> 
> But I have this patch from Laurent queued, which already reworks things:
> 
>   https://patchwork.ozlabs.org/patch/1055996/
> 
> 
> Does that address your problem?

Yes, I should have seen this earlier.

Regards,
Bharata.

Re: [PATCH] powerpc/pseries: Provide verbose info about HPT resizing attempt

[Michael Ellerman]

Bharata B Rao <bharata@linux.ibm.com> writes:

> When HPT resizing is attempted in response to memory hotplug, we see
> the following messages from the kernel:
>
> lpar: Attempting to resize HPT to shift 23
> Unable to resize hash page table to target order 23: -28
>
> This gives a feeling as though we are trying to grow HPT but failed and
> hence bad things might happen in future. Improve the message a bit
> by explicitly printing the existing HPT shift value in addtion to
> the newly targeted value so that it is clear that we haven't failed
> to grow HPT. After this commit, the same message will appear like this:
>
> lpar: Attempting to resize HPT from shift 25 to 23
> Unable to resize hash page table to target order 23: -28
>
> Signed-off-by: Bharata B Rao <bharata@linux.ibm.com>

I'd be inclined to just remove the "Attempting .." message.

But I have this patch from Laurent queued, which already reworks things:

  https://patchwork.ozlabs.org/patch/1055996/


Does that address your problem?

cheers

> diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
> index f2a9f0adc2d3..ecc7fa1876a9 100644
> --- a/arch/powerpc/platforms/pseries/lpar.c
> +++ b/arch/powerpc/platforms/pseries/lpar.c
> @@ -875,7 +875,8 @@ static int pseries_lpar_resize_hpt(unsigned long shift)
>  	if (!firmware_has_feature(FW_FEATURE_HPT_RESIZE))
>  		return -ENODEV;
>  
> -	pr_info("Attempting to resize HPT to shift %lu\n", shift);
> +	pr_info("Attempting to resize HPT from shift %llu to %lu\n", ppc64_pft_size,
> +		shift);
>  
>  	t0 = ktime_get();
>  
> -- 
> 2.17.1