Date: Fri, 4 Jan 2008 13:24:28 +0000 (GMT) From: Robert Watson <rwatson@FreeBSD.org> To: =?utf-8?Q?Dag-Erling_Sm=C3=B8rgrav?= <des@des.no> Cc: Poul-Henning Kamp <phk@phk.freebsd.dk>, freebsd-current@freebsd.org, Jason Evans <jasone@freebsd.org>, Igor Mozolevsky <igor@hybrid-lab.co.uk> Subject: Re: sbrk(2) broken Message-ID: <20080104132310.X77222@fledge.watson.org> In-Reply-To: <86abnlag4t.fsf@ds4.des.no> References: <86myrlahee.fsf@ds4.des.no> <5647.1199451237@critter.freebsd.dk> <a2b6592c0801040503j650046f5k73895b5b0c84025d@mail.gmail.com> <86abnlag4t.fsf@ds4.des.no>
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This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --621616949-924143580-1199453068=:77222 Content-Type: TEXT/PLAIN; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE On Fri, 4 Jan 2008, Dag-Erling Sm=F8rgrav wrote: > "Igor Mozolevsky" <igor@hybrid-lab.co.uk> writes: >> This makes memory management in the userland hideously and unnecessarily= =20 >> complicated. It's simpler to have SIGDANGER [...] > > You don't seem to understand what Poul-Henning was trying to point out,= =20 > which is that broadcasting SIGDANGER can make a bad situation much, much= =20 > worse by waking up and paging in every single process in the system,=20 > including processes that are blocked and wouldn't otherwise run for sever= al=20 > minutes, hours or even days (getty, inetd, sshd, mountd, even nfsd / nfsi= od=20 > in some cases can sleep for days at a time waiting for I/O) Another aspect of the problem is that applications have come to depend in= =20 malloc(3) returning NULL when memory is getting tight, and while we have ne= ver=20 done exactly that, we have historically had malloc(3) return NULL when we g= et=20 close to the process data segment size. Robert N M Watson Computer Laboratory University of Cambridge --621616949-924143580-1199453068=:77222--
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