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Failed to connect to MySQL: (1203) User howardkn already has more than 'max_user_connections' active connectionsPath: ...!news.misty.com!weretis.net!feeder9.news.weretis.net!i2pn.org!i2pn2.org!.POSTED!not-for-mail From: mitchalsup@aol.com (MitchAlsup1) Newsgroups: comp.arch Subject: Re: Address bits again, Article on new mainframe use Date: Wed, 4 Sep 2024 16:51:15 +0000 Organization: Rocksolid Light Message-ID: <470504a11423b97edf0ecdf6b41197d1@www.novabbs.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Info: i2pn2.org; logging-data="850421"; mail-complaints-to="usenet@i2pn2.org"; posting-account="65wTazMNTleAJDh/pRqmKE7ADni/0wesT78+pyiDW8A"; User-Agent: Rocksolid Light X-Rslight-Site: $2y$10$M0snGyeoIaqtKkOvPuNDNO2i6xc6TNSWRszp8f7w/gRpQvGEqDGue X-Spam-Checker-Version: SpamAssassin 4.0.0 X-Rslight-Posting-User: ac58ceb75ea22753186dae54d967fed894c3dce8 Bytes: 2891 Lines: 46 On Wed, 4 Sep 2024 15:38:00 +0000, John Dallman wrote: > In article , johnl@taugh.com (John Levine) > wrote: > >> I think they thought it was paging, but of course 8K pages were way >> too large. So they overreacted and the Vax pages were 512 bytes >> which were too small. > > Everyone seems to use 4K pages now, and that works well for > ordinary-size > programs in 32- and 64-bit address spaces. Bigger pages have been > available in many operating systems for a couple of decades, but they > seem to have been only used by programs that used memory in specialised > ways, like database indexes, and they were used on a per-process basis. For better or worse, My 66000 uses 8K pages. This has several advantages:: a) it is a 5 level structure for a 63-bit virtual address space (instead of 6) b) each level gives you 1024 DoubleWords (instead of 512) 10 is easier for humans to reason about than 9 c) page sizes ae 8K, 8M, 8G, 8T, 8E, really big easier to reason through d) nested page walks are 5×5 instead of 6×6 e) 1 more bit for doing something different. With level skipping one can map 'cat" in 1 page of MMY tables {one page of paging overhead}, and still scatter .code far from .data and .stack or .heap. > The interesting thing that's happening now is that Android 15, due for > release soon, allows for devices that /only/ use 16K pages. Since > there's > no conventional paging, they presumably want to keep the page tables > from > eating too much RAM. > >> When I was working on the DOS version of Javelin we used a linker >> that had overlays just like the mainframe linkers. I got it to work >> and squeezed the code into about 1/3 the space it'd take otherwise >> but it wasn't pleasant. > > Was that PLink, the Phoenix linker? The project I worked on in 1986-87 > used that for similar squashing. > > John