On Thu, 2 Dec 2021 21:05:01 +0300 ValdikSS <iam@xxxxxxxxxxxxxxx> wrote: > This patchset is surprisingly effective and very useful for low-end PC > with slow HDD, single-board ARM boards with slow storage, cheap Android > smartphones with limited amount of memory. It almost completely prevents > thrashing condition and aids in fast OOM killer invocation. > > The similar file-locking patch is used in ChromeOS for nearly 10 years > but not on stock Linux or Android. It would be very beneficial for > lower-performance Android phones, SBCs, old PCs and other devices. > > With this patch, combined with zram, I'm able to run the following > software on an old office PC from 2007 with __only 2GB of RAM__ > simultaneously: > > * Firefox with 37 active tabs (all data in RAM, no tab unloading) > * Discord > * Skype > * LibreOffice with the document opened > * Two PDF files (14 and 47 megabytes in size) > > And the PC doesn't crawl like a snail, even with 2+ GB in zram! > Without the patch, this PC is barely usable. > Please watch the video: > https://notes.valdikss.org.ru/linux-for-old-pc-from-2007/en/ > This is quite a condemnation of the current VM. It shouldn't crawl like a snail. The patch simply sets hard limits on page reclaim's malfunctioning. I'd prefer that reclaim not malfunction :( That being said, I can see that a blunt instrument like this would be useful. I don't think that the limits should be "N bytes on the current node". Nodes can have different amounts of memory so I expect it should scale the hard limits on a per-node basis. And of course, the various zones have different size as well. We do already have a lot of sysctls for controlling these sort of things. Was much work put into attempting to utilize the existing sysctls to overcome these issues?
