Re: [RFC] powerpc/hugetlb: Add warning message when gpage allocation request fails

On 14.09.2015 [18:59:25 +0530], Aneesh Kumar K.V wrote:

Anshuman Khandual [off-list ref] writes:

quoted

When a 16GB huge page is requested on POWER platform through kernel command
line interface, it silently fails because of the lack of any gigantic pages
on the system which the platform should have communicated through 16GB memory
blocks in the device tree during boot time. For example

[    0.480940] HugeTLB registered 16 GB page size, pre-allocated 0 pages
[    0.480945] HugeTLB registered 16 MB page size, pre-allocated 16 pages

This adds a warning message during alloc_bootmem_huge_page request both on
book3e and book3s powerpc platforms. After this change

[    0.000000] Gigantic HugeTLB page not available
[    0.473417] HugeTLB registered 16 GB page size, pre-allocated 0 pages
[    0.473423] HugeTLB registered 16 MB page size, pre-allocated 16 pages

That info is already part of the second line isn't it ? ie

[    0.473417] HugeTLB registered 16 GB page size, pre-allocated 0 pages

pre-allocated 0 pages indicate we didn't allocate anything. So why do we
need to add more details fo kernel output ?

Agreed, the '0 pages' message indicates we failed to pre-allocate any
pages. The 'pre-allocate' messages are specifically about the kernel
command-line requests for hugepages.

Not sure I understand the motivation for this?

-Nish