Date: Mon, 28 Dec 2020 23:25:48 +0000 (UTC) From: doug <doug@fledge.watson.org> To: freebsd-questions@FreeBSD.org Subject: Observations on virtual memory operations Message-ID: <167603f-a82a-7031-6850-2d08f17a36@fledge.watson.org>
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I have two servers running jails that "routinely" run out of swapspace with no demand paging activity. To try and get a handle on VM/swapspace management I have been tracking swapinfo vs memory use as measured by top. The numbers do not exactly add up but I assume that is not involved in my issue. The system: real memory = 8589934592 (8192 MB) avail memory = 8248696832 (7866 MB) In top the sum of Active, Inactive, Laundry, Wired, Buf and Free is almost constant between 8704 and 8706 MB. Wired+Buf is fairly constant around 2200MB. Free has no relation to anything as long as the system is working (e.g., what you would expect). The other day I caught the system at 73% swapspace used. At this level the system was in a near thrashing state in that typing a key got it echoed in 10 <--> 30 seconds. There was about 600MB of swapspace at this point. I would think there is no way to debug this except as a thought experiment. My other thought is it would be nice if after perhaps 5,000 -> 10,000 'out of swap space message' logging could stop. I read a google post suggesting this can be handled by logging the console output to a file. Does anyone have experience with this? Right now we are surviving by email warnings when the system gets to 50% swap used and monitoring,
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