Date: Mon, 7 Nov 2022 20:38:17 -0800 From: bob prohaska <fbsd@www.zefox.net> To: Mark Millard <marklmi@yahoo.com> Cc: Mike Karels <mike@karels.net>, freebsd-arm@freebsd.org Subject: Re: adding swap when expanding root filesystem Message-ID: <20221108043817.GA55121@www.zefox.net> In-Reply-To: <09E80B35-0325-44E6-8191-55DCC79A51F1@yahoo.com> References: <202211071610.2A7GAcHl090048@mail.karels.net> <20221107175206.GA49113@www.zefox.net> <78C2FBC4-D2CE-44B0-9535-02C0EDECD10A@karels.net> <20221107205150.GA53784@www.zefox.net> <09E80B35-0325-44E6-8191-55DCC79A51F1@yahoo.com>
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On Mon, Nov 07, 2022 at 04:07:08PM -0800, Mark Millard wrote: > On Nov 7, 2022, at 12:51, bob prohaska <fbsd@www.zefox.net> wrote: > > > On Mon, Nov 07, 2022 at 12:47:29PM -0600, Mike Karels wrote: > >> On 7 Nov 2022, at 11:52, bob prohaska wrote: > >> > >>> On Mon, Nov 07, 2022 at 10:10:38AM -0600, Mike Karels wrote: > > [snip] > > > >>>> I have a prototype, > >>>> and wondered if this is a good thing to do. Granted, this will often > >>>> create swap on microSD, which is not optimal, but probably better than > >>>> nothing. > >>>> > > [snip] > > > > Definitely better than nothing. I think it's a good thing to do. > > > >>>> The current prototype creates a swap partition which is 1/10 of the disk > >>>> if the disk is at least 15 GB and the initial root partition is no more > >>>> than 1/3 of the disk, but only up to 1.5x of physical memory. I would > >>>> probably enable this by default, but provide a way to disable it via a > >>>> kenv variable and/or a variable in /etc/rc.conf. > >>>> > >>>> Thoughts? > >>> > > > > "Yes, please!". I'd suggest 2-4x physical RAM rather than 1.5x, > > simply because extra swap is harmless and microSD cards are > > amply large; 64GB was about the smallest readily available > > last time I looked. Now it's probably 128GB. > > > > It might be wise to add a warning about flash wearing out, > > but it took a year of near-continuous buildworlds to kill > > a 128GB microSD holding -current on a Pi3 with ~3 GB swap. > > > > Anything done to make FreeBSD work better on Raspberry Pi > > and competitors is worth a try. Running from microSD isn't > > ideal but does work if used gently. It worked much better > > under armv7. Between aarch64 and growth in compilers > > working swap seems essential now, the more the better. > > > >>> For starters, is there any hope of making bsdinstall run from the > >>> microSD and installing FreeBSD via the traditional process on USB? > > [snip] > >> > >> I think that???s a completely different problem. I suspect that this > >> is already possible, fetching packages over the net, but I don???t > >> know the incantation. Ideally the packages would be local, but then > >> the image would be more like a CD-ROM. It would be nice to have > >> a procedure documented though. > >> > > Since there's a complete system on the microSD can't that be used > > as the initial repository? > > > > I agree it is a different problem in terms of implementation. > > If bsdinstall can format a boot device for Raspberry Pi I should > > give it a try. > > Remember that bsdinstall does not deal with U-Boot > installation in general. Ok, I'll give up hope for now. [snip] > Also the amount of space > U-Boot and the like takes varies. The Rock64 images > use a 16 MiByte space for its U-Boot and the like, > which are stored outside any file system. I'm not sure how anything can be stored "outside any filesystem". Might it be better to say "in a private filesystem", as in not known to the running kernel? Is there any basic problem with automatically establishing a swap partition during a microSD card setup? A trio of self- hosted armv7 Pi2's with swap on microSD have been running happily for over two years as name, mail and webservers on 64 GB cards. Admittely, aarch64 is a lot more swap-intensive, but a Pi3 ran for about a year on a 128 GB card before things started going wrong. That Pi3 was running buildworld most of the time. The Pi2's df outputs are now straddling 50% capacity without any cleanup, so it's probably time to think about upgrading the storage in some way. Treating microSD as a write-once medium isn't outrageous and it may be prudent for shingled mechnical disks. Configuring swap manually on a RPi microSD system is a very considerable amount of work. Having it happen by default wastes at most a few percent of the card capacity. At this point I can't see any reason to say it's a bad idea and have some personal experience to suggest it's a good idea. [bsdinstall limitations snipped] It might be worth mentioning the /boot/loader.conf and /etc/sysctl.conf additions you've mentioned in other threads, as adjuncts to having autoconfigured swap on microSD. They've all been helpful in my experiments on RPi2 and RPi3. I think they'd be constructive additions to the RPi images and perhaps others.. Thanks for reading, and all your help! bob prohaska
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