Date: Mon, 28 Dec 2020 15:36:59 -0800 From: Pete Wright <pete@nomadlogic.org> To: doug@safeport.com, freebsd-questions@FreeBSD.org Subject: Re: Observations on virtual memory operations Message-ID: <8f3a278a-56cd-c732-68a0-cf6fa5d50a3f@nomadlogic.org> In-Reply-To: <167603f-a82a-7031-6850-2d08f17a36@fledge.watson.org> References: <167603f-a82a-7031-6850-2d08f17a36@fledge.watson.org>
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On 12/28/20 3:25 PM, doug wrote: > 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. > <snip> > > 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. The first thing that comes to mind is do you have the ability to hook any metrics/monitoring onto this system. For example, I use collectd on my systems to report overall CPU/memory metrics as well as per-process memory metrics. Alternatively you could write a simple shell script that run's "ps" and parses the output of memory utilization on a per-process basis. either of the above approaches should give you some insight into where the memory leak is coming from (assuming you already do not know). one trick i use is to invoke a process with "limits" to ensure it does not exceed a certain amount of memory that I allocate to it. for example with firefox i do this: $ limits -m 6g -v 6g /usr/local/bin/firefox that should at least buy you enough time to investigate why the process needs so much memory and see what you can do about it. -p -- Pete Wright pete@nomadlogic.org @nomadlogicLA
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