Date: Sat, 10 Nov 2012 09:43:48 -0800 From: Peter Wemm <peter@wemm.org> To: Ian Lepore <freebsd@damnhippie.dyndns.org> Cc: src-committers@freebsd.org, Eitan Adler <eadler@freebsd.org>, Alfred Perlstein <alfred@freebsd.org>, svn-src-all@freebsd.org, Alfred Perlstein <bright@mu.org>, svn-src-head@freebsd.org Subject: Re: svn commit: r242847 - in head/sys: i386/include kern Message-ID: <CAGE5yCp4N7fML05-Tomm0TM-ROBSka5%2Bb9EKJTFR%2ByUpFuGj5Q@mail.gmail.com> In-Reply-To: <1352568275.17290.85.camel@revolution.hippie.lan> References: <201211100208.qAA28e0v004842@svn.freebsd.org> <CAF6rxg=HPmQS1T-LFsZ=DuKEqH30iJFpkz%2BJGhLr4OBL8nohjg@mail.gmail.com> <509DC25E.5030306@mu.org> <509E3162.5020702@FreeBSD.org> <509E7E7C.9000104@mu.org> <CAF6rxgmV8dx-gsQceQKuMQEsJ%2BGkExcKYxEvQ3kY%2B5_nSjvA3w@mail.gmail.com> <509E830D.5080006@mu.org> <1352568275.17290.85.camel@revolution.hippie.lan>
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On Sat, Nov 10, 2012 at 9:24 AM, Ian Lepore <freebsd@damnhippie.dyndns.org> wrote: > On Sat, 2012-11-10 at 08:38 -0800, Alfred Perlstein wrote: >> On 11/10/12 8:25 AM, Eitan Adler wrote: >> > On 10 November 2012 11:19, Alfred Perlstein <bright@mu.org> wrote: >> >> Please consult the svn log for this file, it's relatively clear >> just in the >> >> commit logs/comments. Grep for 384/512 and look around. >> > Can this reasoning be added as a comment? I did grep for 384 in the >> log, but >> > a) I didn't find the answer >> > b) one shouldn't have to. >> > >> > >> It probably could be added, but then a bunch of other people would >> complain about the comment being too wordy or "not in English". > > The fact that such a thing could happen explains much about the current > state of the code. An outsider could easily come to the conclusion that > the FreeBSD motto is something along the lines of "It should be as hard > to read as it was to write." Don't forget to explain that you get 1 maxusers per 2MB of physical memory which turns into 64 x 2k clusters and a whole series of side effects. Wouldn't it be nice if we could write "By default, mbuf clusters are capped at 6% of physical ram or 6% of kernel address space, whichever is smaller" ? That's a little easier than trying to explain maxusers = physpages / (2 * 1024 * 1024 / PAGE_SIZE) if (maxusers > 384) maxusers = 384 + ((maxusers - 384) / 8); nmbclusters = 1024 + maxusers * 64; I'd sure prefer to explain: /* pick smaller of kva pages or physical pages */ if ((physpages / 16) < (kvapages / 16)) nmbclusters = physpages / 16; else nmbclusters = kvapages / 16; Leave maxusers for calculating maxproc. -- Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com; KI6FJV "All of this is for nothing if we don't go to the stars" - JMS/B5 "If Java had true garbage collection, most programs would delete themselves upon execution." -- Robert Sewell
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