Messages in this thread | | | Subject | Re: [PATCH] mm/gup_benchmark: GUP_BENCHMARK depends on DEBUG_FS | From | John Hubbard <> | Date | Sat, 7 Nov 2020 11:16:51 -0800 |
| |
On 11/7/20 11:05 AM, Song Bao Hua (Barry Song) wrote: >> -----Original Message----- >> From: John Hubbard [mailto:jhubbard@nvidia.com] ... >>> config GUP_BENCHMARK >>> bool "Enable infrastructure for get_user_pages() and related calls >> benchmarking" >>> + depends on DEBUG_FS >> >> >> I think "select DEBUG_FS" is better here. "depends on" has the obnoxious >> behavior of hiding the choice from you, if the dependencies aren't already met. >> Whereas what the developer *really* wants is a no-nonsense activation of the >> choice: "enable GUP_BENCHMARK and the debug fs that it requires". >> > > To some extent, I agree with you. But I still think here it is better to use "depends on". > According to > https://www.kernel.org/doc/Documentation/kbuild/kconfig-language.txt > > select should be used with care. select will force > a symbol to a value without visiting the dependencies. > By abusing select you are able to select a symbol FOO even > if FOO depends on BAR that is not set. > In general use select only for non-visible symbols > (no prompts anywhere) and for symbols with no dependencies. > That will limit the usefulness but on the other hand avoid > the illegal configurations all over. > > On the other hand, in kernel there are 78 "depends on DEBUG_FS" and > only 14 "select DEBUG_FS". >
You're not looking at the best statistics. Go look at what *already* selects DEBUG_FS, and you'll find about 50 items.
thanks, -- John Hubbard NVIDIA
| |