Date: Wed, 20 Apr 2016 09:17:06 -0600 From: Warner Losh <imp@bsdimp.com> To: Konstantin Belousov <kostikbel@gmail.com> Cc: Ian Lepore <ian@freebsd.org>, Allan Jude <allanjude@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org> Subject: Re: svn commit: r298230 - in head: lib/libstand sys/boot/common sys/boot/efi/libefi sys/boot/efi/loader sys/boot/i386/libfirewire sys/boot/i386/libi386 sys/boot/i386/loader sys/boot/mips/beri/loader sy... Message-ID: <CANCZdfpv%2BRoY7vdmQM0%2By19JLErr%2BDzEgoWEUXPz0qB=vbx6UQ@mail.gmail.com> In-Reply-To: <20160420084542.GC2422@kib.kiev.ua> References: <201604182309.u3IN9MC6047480@repo.freebsd.org> <CAJ-Vmo=WX8xwnuvbPJMib3BMuVKjQMkKt1qXkx=TPH5wZYPM1A@mail.gmail.com> <57157108.6090500@freebsd.org> <20160419093022.GV2422@kib.kiev.ua> <5716538B.4060108@freebsd.org> <1461086958.1232.30.camel@freebsd.org> <20160420084542.GC2422@kib.kiev.ua>
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On Wed, Apr 20, 2016 at 2:45 AM, Konstantin Belousov <kostikbel@gmail.com> wrote: > On Tue, Apr 19, 2016 at 11:29:18AM -0600, Ian Lepore wrote: > > On Tue, 2016-04-19 at 11:49 -0400, Allan Jude wrote: > > > On 2016-04-19 05:30, Konstantin Belousov wrote: > > > > On Mon, Apr 18, 2016 at 07:43:04PM -0400, Allan Jude wrote: > > > > > On 2016-04-18 19:36, Adrian Chadd wrote: > > > > > > Someone pointed out how this bloats out memory requirement in > > > > > > loader. > > > > > > > > > > > > Did anyone check that? > > > > > > > > > > > > -adrian > > > > > > > > > > > > > > > > I tested down to 128mb of ram in QEMU, booted from the installer > > > > > ISO, > > > > > did the install, and booted the installed system without issue. > > > > > > > > 64MB is^H^H was very much useful and workable i386 config. i386 > > > > kernel > > > > does fit into the 32M but current automatic tuning prevents > > > > usermode > > > > from operating. Little manual tuning make 32M on tolerable. > > > > > > > > Making loader require 64M is a regression. At very least, it is > > > > impossible to test low mem configs anymore. > > > > > > > > > > Would a src.conf knob make sense, to use a smaller value when > > > targeting > > > small systems, while keeping the advantages when using more > > > reasonable > > > systems? > > > > > > Or we could make these changes to the HEAP and bcache size specific > > > to > > > 64bit platforms? > > > > > > > Exactly which "small systems" are we talking about here? From what I > > saw in the commit, all of this affects only i386 and amd64 and pc98 > > right now, not arm or mips or other systems that often have < 64MB ram. > > > > I take care of some really old legacy embedded systems at customer > > sites, and even so, with stuff dating back to the 2003-ish timeframe, > > the smallest i386 memory I have to deal with is 64MB. Are there really > > x86 systems that need to run in 32MB or less of ram these days, and use > > BIOS or EFI to boot? > Most of the VM/core system work is performed on the x86 machines, I mean > the debugging and testing, and not compiling. Consider this first-hand > experience. > > That is, not being able to check a change on 32MB x86 machine means, > for significant number of developers, that the change cannot be tested > on 32M machine at all. I leave the exercise of predicting the FreeBSD > behaviour on 32MB MIPS or ARM arches, after the x86 is left to require > 128MB at least for several months, to interested readers. > > What I wrote above is the only my concern, I do not know for sure if there > are any production-important installations where x86 FreeBSD of recent > versions run on, say, 64MB. As I noted elsewere, 64MB is enough to have > userspace fully operational. 32MB is not, but it is still useful for > kernel-only use. 32MB on arm is tight. Some heroics on tuning and you can still run on 32MB boards. But it is a lot of heroics, at least for ARM. Some minor tweaking gets 64MB to perform well, at least for the DNS / DHCP server I run on mine. Warner
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