On Sun, Feb 04, 2024 at 09:34:01PM +0000, Matthew Wilcox wrote: > On Sun, Feb 04, 2024 at 11:39:33AM +0100, Mike Rapoport wrote: > > On Mon, Jan 29, 2024 at 04:32:03AM +0000, Matthew Wilcox wrote: > > > Our documentation of the current page flags is ... not great. I think > > > I can improve it for the page cache side of things; I understand the > > > meanings of locked, writeback, uptodate, dirty, head, waiters, slab, > > > mlocked, mappedtodisk, error, hwpoison, readahead, anon_exclusive, > > > has_hwpoisoned, hugetlb and large_remappable. > > > > > > Where I'm a lot more shaky is the meaning of the more "real MM" flags, > > > like active, referenced, lru, workingset, reserved, reclaim, swapbacked, > > > unevictable, young, idle, swapcache, isolated, and reported. > > > > > > Perhaps we could have an MM session where we try to explain slowly and > > > carefully to each other what all these flags actually mean, talk about > > > what combinations of them make sense, how we might eliminate some of > > > them to make more space in the flags word, and what all this looks like > > > in a memdesc world. > > > > > > And maybe we can get some documentation written about it! Not trying > > > to nerd snipe Jon into attending this session, but if he did ... > > > > I suspect Jon will be there anyway, but not sure he'd be willing to do the > > writing :) > > > > I was going to propose the "mm docs" session again, but this one seems more > > useful than talking yet again about how hard it is to get MM documentation > > done. > > I'm doing my best to write documentation as I go. I think we're a bit > better off than we were last year. Do we have scripts to tell us which > public functions (ie EXPORT_SYMBOL and static inline functions in header > files) have kernel-doc? And could we run them against kernels from, say, > April 2023, 2022, 2021, 2020, 2019 (and in two months against April 2024) > and see how we're doing in terms of percentage undocumented functions? We didn't have such script, but it was easy to compare "grep EXPORT_SYMBOL\|static inline" with ".. c:function" in kernel-doc. We do improve slowly, but we are still below 50% with kernel-doc for EXPORT_SYMBOL functions and slightly above 10% for static inlines. Although with static inlines it's quite possible that the percentage of actual public API documentation is higher because some of the functions in inlcude/linux/ are only used inside mm. There are also APIs that are not EXPORT_SYMBOL, but I didn't find an easy way to check how well there are documented. EXPORT_SYMBOL version funcs docs percent v5.0 514 177 34 v5.6 538 208 38 v5.12 550 209 38 v5.17 580 228 39 v6.3 580 235 40 v6.8-rc1 565 238 42 static inline version funcs docs percent v5.0 581 33 5 v5.6 596 41 6 v5.12 629 42 6 v5.17 746 74 9 v6.3 867 95 10 v6.8-rc1 944 116 12 > There's also the problem of getting long-form documentation done. > But I think that's a different problem from getting kernel-doc written. > Looking at the 55 commits in the last year to Documentation/mm, we seems > to be doing a pretty good job of keeping the documentation we have up > to date. Just not a great job of adding new documentation. I agree that long-form documentation is a different problem from getting kernel-doc written and we are not doing a great job in writing new documentation. -- Sincerely yours, Mike.
