Hello. On čtvrtek 2. prosince 2021 22:58:24 CET Andrew Morton wrote: > 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. Probably not. To my understanding, the limits should roughly correspond to what you see after executing this: ``` $ echo 1 | sudo tee /proc/sys/vm/drop_caches; grep -F 'Active(file)' /proc/ meminfo ``` IMO, this has nothing to do with the size of the node. > 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? -- Oleksandr Natalenko (post-factum)
