Date: Sun, 18 May 1997 23:24:40 -0500 (EST) From: "John S. Dyson" <toor@dyson.iquest.net> To: davem@caip.rutgers.edu (David S. Miller) Cc: dyson@FreeBSD.ORG, terry@lambert.org, deischen@iworks.InterWorks.org, freebsd-hackers@FreeBSD.ORG, jb@freebsd1.cimlogic.com.au Subject: Re: GNAT-pthreads integration bugs/questions Message-ID: <199705190424.XAA10492@dyson.iquest.net> In-Reply-To: <199705190345.XAA16247@darkwing.rutgers.edu> from "David S. Miller" at "May 18, 97 11:45:28 pm"
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> > kernel address space for anything is bad news on SMP, I don't care > what kind of optimizations you put into the SMP tlb flushing code in a > kernel that does VM based VFS operations (and yes I am intimately > familiar with all the gross hacks SVR4 etc. put into their code to try > and fight this problem, it just doesn't work), it will never perform > adequately. > That's the reason that we don't do it. I don't like the approach that SVR4 used (it is even slow in the UP case.) There are individuals that still think that we fault pages into the kernel for file I/O or some other wierd unnecessarily complicated thing (even though it does work nicely.) I have taken heat from time to time for not faulting pages into the kernel for file I/O. Much of the complication in the FreeBSD code is to support sub-pagesize filesystem block sizes and maintain full file I/O and mmap coherency. John
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