Struct page cleanup [LWN.net]

Struct page cleanup

Posted May 1, 2018 11:16 UTC (Tue) by Sesse (subscriber, #53779)
In reply to: Struct page cleanup by willy
Parent article: Willy's memory-management to-do list

Maybe you should add an extra blank line after the flags, to point out that the numbering no longer matters there?

Also, I wonder, why are people all “WE ARE OUT OF PAGE FLAGS” all the time, when there are clearly tons of them left for 64-bit and a bunch even for 32-bit?

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Struct page cleanup

Posted May 1, 2018 11:49 UTC (Tue) by willy (subscriber, #9762) [Link] (2 responses)

I've added the blank line as requested. I think that improves things for people following along at home, but I'm not sure it would have fit on the projector's screen :-)

My slot wasn't focused on the flags, so I didn't fill in all the rest of the details; I juts handwaved at it because everybody else in the room knew what other things were in those bits. I've filled in the fields that are commonly stored in those bits; the problem is that they're all dependent on various CONFIG options and I haven't taken the trouble to figure out likely values in order to size the fields to realistic number of bits. If you can make sense of page-flags-layout.h and the rest of the generating machinery, please let me know. The first problem you'll face is that whoever did the ASCII art in those files was a fan of big-endian bit numbering (probably from IBM).

Struct page cleanup

Posted May 1, 2018 11:51 UTC (Tue) by Sesse (subscriber, #53779) [Link] (1 responses)

Thanks! That made it clearer for me, at least. :-)

Struct page cleanup

Posted May 1, 2018 12:23 UTC (Tue) by willy (subscriber, #9762) [Link]

Excellent! Thanks for the constructive criticism!