Date: Mon, 29 Jun 2020 15:22:22 -0700 From: Mark Millard <marklmi@yahoo.com> To: dwilde1@gmail.com Cc: freebsd-stable@freebsd.org Subject: Re: swap space issues Message-ID: <13D7C246-9842-4DFA-92EB-7161F52ED39E@yahoo.com> In-Reply-To: <CAEC7392ZVv%2BZyOF_Y%2BUfDLfw6uAkQW7skvE4jJu7=kPcGCC=%2Bw@mail.gmail.com> References: <EEE87A3D-5E15-4D88-AF7D-E48F9440CF54.ref@yahoo.com> <EEE87A3D-5E15-4D88-AF7D-E48F9440CF54@yahoo.com> <CAEC7393eRE9DaUq1P_KoEPBtUQoi%2BsQa6QtbNyNFS-nv04sX3g@mail.gmail.com> <2D0E1E39-2607-4D62-A232-F39C6BE1CC0D@yahoo.com> <CAEC7392ZVv%2BZyOF_Y%2BUfDLfw6uAkQW7skvE4jJu7=kPcGCC=%2Bw@mail.gmail.com>
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On 2020-Jun-29, at 14:12, Donald Wilde <dwilde1 at gmail.com> wrote: > On 6/29/20, Mark Millard <marklmi at yahoo.com> wrote: >> [I'm now subscribed so my messages should go through to >> the list.] >> >> On 2020-Jun-29, at 06:17, Donald Wilde <dwilde1 at gmail.com> wrote: >> >>> . . . >> >> You report using: >> >> # For possibly insufficient swap/paging space >> # (might run out), increase the pageout delay >> # that leads to Out Of Memory killing of >> # processes: >> vm.pfault_oom_attempts= 10 >> vm.pfault_oom_wait= 1 >> # (The multiplication is the total but there >> # are other potential tradoffs in the factors >> # multiplied for the same total.) >> >> Note: kib might be interested in what happens >> for, say, 10 and 1, 5 and 2, and 1 and 10. >> He has asked for such before from someone >> having OOM problems but, to my knowledge, >> no one has taken him up on such testing. >> (He might be only after 10/1 and 1/10 or >> other specific figures. Best to ask him if >> you want to try such things for him.) > > Who is 'kib'? I'm still learning the current team of the Project. Konstantin Belousov Also known as kib (from kib at freebsd.org). Also known as kostik (from part of his gmail address?). >> I've always set up to use vm.pfault_oom_attempts=-1 >> (avoiding running out of swap space by how I >> configure things and what I choose to run). I >> avoid things like tempfs that compete for RAM, >> especially in low memory contexts. > > Until you explained what you have taught me, I thought these were > swap-related issues. > > TBH, I am getting disgusted with Synth, as good as it (by spec, not > actuality) is supposed to be. While I experimented with Synth a little a long time ago, I normally stick to tools and techniques that work across amd64, powerpc64, aarch64, 32-bit powerpc, and armv7 when I can. So, the experiment was strictly temporary on one environment at the time. > CCache I've used for years, and never had this kind of issue. >> >> For 64-bit environments I've never had to have >> enough swapspace that the boot reported an issue >> for kern.maxswapzone : more swap is allowed for >> the same amount of RAM as is allowed for a 32-bit >> environment. > > Now that you've opened the possibility, it would explain how it goes > from <3% swap use to OOM in moments... it's not a swap usage issue! > That's an important thing to learn. > > Not having heard from anyone else, I'm in the process of zeroing my > drive and starting over. >> >> In the 64-bit type of context with 1 GiByte+ >> of RAM I do -j4 build world buildkernel, 3072 MiBytes >> of swap. For 2 GiByte+ of RAM I use 4 poudriere builders >> (one per core), each allowed 4 processes >> (ALLOW_MAKE_JOBS=yes), so the load average can at times >> reach around 16 over significant periods. I also use >> USB SSDs instead of spinning rust. The port builds >> include a couple of llvm's and other toolchains. But >> there could be other stuff around that would not fit. >> >> (So synth for you vs. poudriere for me is a >> difference in our contexts. ALso, I stick to >> default kern.maxswapzone use without boot >> messages about exceeding the maximum >> recommended amount. Increasing kern.maxswapzone >> trades off KVM available for other purposes and >> I avoid the tradeoffs that I do not understand.) > [snip] >> (My context is head, not stable.) > > Thanks for documenting your usage. I'll store a pointer to this week's > -stable archives so I can come back to this when I get to smaller > builds. >> >> . . . >> >>> What got corrupted was one of the /usr/.ccache directories, but >>> 'ccache -C' doesn't clear it. >> >> I've not used ccache. So that is another variation >> in our contexts. >> >> I use UFS, not ZFS. I avoid tmpfs and such that complete >> for memory. > > I'm using UFS on MBR partitions. GPT for root file systems for me, other than any old PowerMacs (APM). (On the small arm's I just use microsd cards to get to booting the root file system on a GPT based USB SSD via a technique that works the same for all such arms that I sometimes have access to, other than the RPi4's at this stage.) >> . . . === Mark Millard marklmi at yahoo.com ( dsl-only.net went away in early 2018-Mar)
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