Date: Fri, 24 Aug 2012 17:10:01 -0700 From: Colin Percival <cperciva@freebsd.org> To: John Baldwin <jhb@freebsd.org> Cc: alc@freebsd.org, =?UTF-8?B?RGFnLUVybGluZyBTbcO4cmdyYXY=?= <des@des.no>, freebsd-current@freebsd.org Subject: Re: Time to bump default VM_SWZONE_SIZE_MAX? Message-ID: <503817D9.3070006@freebsd.org> In-Reply-To: <201208241013.48805.jhb@freebsd.org> References: <502831B7.1080309@freebsd.org> <201208240748.19737.jhb@freebsd.org> <866288laq0.fsf@ds4.des.no> <201208241013.48805.jhb@freebsd.org>
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On 08/24/12 07:13, John Baldwin wrote:=0D > On Friday, August 24, 2012 8:45:43 am Dag-Erling Sm=C3=B8rgrav wrote:=0D >> John Baldwin <jhb@freebsd.org> writes:=0D >>> Note that on i386 you can't get more than 4GB of RAM without PAE, and i= f you=0D >>> have any modern x86 box with > 4GB of RAM, you are most likely running = amd64=0D >>> on it, not i386. I think i386 would be fine to just keep the limit it = had.=0D >>=0D >> The limit we had was insufficient for 8 GB of swap.=0D > =0D > In absolute or practical terms? Not all swap blocks are fully utilized. = At=0D > Y! the install script we used would compute the maximum theoretical swap = zone=0D > needed and then cut it in half, and this worked quite well. Also, keep i= n mind,=0D > this is for i386, not amd64. At this point i386 is going to be used on s= maller=0D > systems (e.g. netbooks, etc.), not servers that have lots of swap.=0D =0D I'd like to see i386 bumped slightly, just so that the rule of "allocate sw= ap=0D space equal to max(RAM, min(2*RAM, 8 GB))" (which I've seen in lots of plac= es)=0D is more likely to be safe. If I'm understanding things correctly, bumping = from=0D 32 MB up to 34.5 MB should give us a theoretical 16 GiB or a "safe" 8 GiB l= imit=0D on swap usage (2^17 structures which are 276 bytes each on i386).=0D =0D But I agree that the real issue was with amd64, not i386.=0D =0D -- =0D Colin Percival=0D Security Officer Emeritus, FreeBSD | The power to serve=0D Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid= =0D
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