Date: Mon, 21 Jan 2019 16:03:02 +0000 From: RW <rwmaillists@googlemail.com> To: freebsd-questions@freebsd.org Subject: Re: The mysterious kern.maxswzone Message-ID: <20190121160302.0a5e2805@gumby.homeunix.com> In-Reply-To: <50f1f8d5-7db6-4abb-6beb-c82f17396304@netfence.it> References: <20190116022046.GA45024@admin.sibptus.ru> <50f1f8d5-7db6-4abb-6beb-c82f17396304@netfence.it>
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On Mon, 21 Jan 2019 08:56:05 +0100 Andrea Venturoli wrote: > On 1/16/19 3:20 AM, Victor Sudakov wrote: > > > > > warning: total configured swap (131072 pages) exceeds maximum > > recommended amount (113792 pages). warning: increase kern.maxswzone > > or reduce amount of swap. > > Many of my systems show this warning: in general it's harmless and > you can ignore it. Do you know, for sure, that there isn't a risk of a panic if you run out of zone space before you run out of swap. > > # sysctl kern.maxswzone > > kern.maxswzone: 36175872 > > This is strange: on all my boxes (all 11.2/amd64) kern.maxswzone=0. > If you did not set this manually (where, I don't know), perhaps this > is an i386 vs amd64 thing. That rings a bell. In i386 kern.maxswzone defaults to that fixed value of 36175872. In other architectures it defaults to zero, which means use a computed amount based on RAM size. In amd64 you can't increase the zone size because that computed default is also the limit. In this case, with i386, 36175872 is below the limit, so you can increase it. The value is in bytes, so it isn't huge. Try setting it to a few percent above 36175872 * 131072 / 113792 something like 42500000 It should be set in loader.conf, not via sysctl.
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