Date: Sun, 19 May 2019 08:34:28 -0700 From: Conrad Meyer <cem@freebsd.org> To: tech-lists <tech-lists@zyxst.net> Cc: "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org> Subject: Re: total configured swap exceeds maximum Message-ID: <CAG6CVpWB3Ugjx7oo43K6NCZjWSRDqo4i_UsxR7peYeqe=NeDmw@mail.gmail.com> In-Reply-To: <20190519125505.GB6971@rpi3.zyxst.net> References: <alpine.BSF.2.20.1905191204540.4805@puchar.net> <20190519125505.GB6971@rpi3.zyxst.net>
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Tangent to this thread, but: On Sun, May 19, 2019 at 5:56 AM tech-lists <tech-lists@zyxst.net> wrote: > Then there's the thing about dump/panic. IIRC doesn't total swap have to > be at least size_of_ram ? It can be smaller if occasional failure is acceptable. Minidumps are on by default and only dump active pages. Additionally, dumpon_flags can set "-Z" for zstd compression in 12.x+. The numeric speed/compression level is configured with sysctl kern.kerneldump_gzlevel (perhaps misnamed at this point, but originally only supported gzip). In practice, Zstd compression can often achieve good compression at level 1 or 3, reducing the size of swap needed to store a complete dump by a factor of maybe 3 without significant slowdown to the dump process. Cheers, Conrad
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