Date: Fri, 14 Feb 2003 10:43:45 -0800 From: David Schultz <dschultz@uclink.Berkeley.EDU> To: The Hermit Hacker <scrappy@hub.org> Cc: freebsd-stable@FreeBSD.ORG Subject: Re: latest kernel issue ... or increased KVA_FILES ... ? Message-ID: <20030214184345.GA1579@HAL9000.homeunix.com> In-Reply-To: <20030214121353.T76487@localhost> References: <20030214065945.L76487@localhost> <20030214115355.GA424@HAL9000.homeunix.com> <20030214121353.T76487@localhost>
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Thus spake The Hermit Hacker <scrappy@hub.org>: > When Tor suggested changing this to me, he mentioned "This reduces the > address space available for userland processes, but very few applications > need more than 1 GB for data in a single process." ... now, if I'm > understanding this correctly, if I set it to 512, a single process won't > be able to exceed 2GB (*very* unlikely), but what happens if it does? > Does the process just crash, but the system remains running? As des mentioned, allocations will fail and the rest depends on how the application handles that. > > Pthreads in 4-STABLE uses the start of the main stack as a basis > > for determining where to put stacks for individual threads that > > are spawned. The value of KVA_PAGES used to be statically > > compiled into pthreads, so you would have to recompile libc every > > time you changed KVA_PAGES. Peter Wemm tried to fix this some > > time ago by reading the value from sysctl instead, but his fix is > > incomplete. The patch in the following PR has been verified (not > > by me) to fix the problem. Hopefully it has not been subject to > > bit rot over the last few months. > > 'K, but as long as I install/upgrade both kernel and world at the same > time, there won't be a problem, right ... ? Right. > > > Similar was happening to the mysqld daemon ... > > > > Random naive question: Postgresql spawns separate processes > > instead of using threads, doesn't it? How has that worked out, > > and is it expected to change? > > Not expected to change, and works quite well ... there has been alot of > work to reduce the start time for the process(es), which used to be alot > of the complaints concerning 'seperate processes' ... there are ppl > talking about working towards the Apache2 model (I'm one of them) where > each process would still only handle one connection, but would be able to > offload some of the processing to other threads, so that they could work > in parrellel ... Cool. I wouldn't expect process startup time to be a big deal unless you have new clients initiating new connections like mad, and I hope that isn't a common case. (Then again, I'm not a database person, and I don't know how e.g. PHP might interact with the database.) The reliability advantage of multiple processes seems important as well. In any case, I will migrate over to the correct lists if I have any more questions about postgresql. ;-) Thanks. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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