From owner-freebsd-questions Sun May 23 11:13:45 1999 Delivered-To: freebsd-questions@freebsd.org Received: from ice.mozcom.com (ice.mozcom.com [202.47.132.42]) by hub.freebsd.org (Postfix) with ESMTP id DB9D614F91 for ; Sun, 23 May 1999 11:13:41 -0700 (PDT) (envelope-from orly@mozcom.com) Received: from ice.mozcom.com (ice.mozcom.com [202.47.132.42]) by ice.mozcom.com (8.9.3/8.9.2) with SMTP id CAA02494 for ; Mon, 24 May 1999 02:21:57 +0800 (PHT) (envelope-from orly@mozcom.com) Date: Mon, 24 May 1999 02:21:57 +0800 (PHT) From: Orlando Andico To: freebsd-questions@freebsd.org Subject: UFS, VM, scheduler, emulation questions Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Hello all, I'm a new FreeBSD user, although I've used Solaris 1 and 2, IRIX 5, and Linux for several years and can probably consider myself an experienced UNIX user. I have several questions about FreeBSD implementations. 1) FreeBSD 3.x ``feels'' faster than Linux on identical hardware. Is this a scheduler feature (similar to Windows NT's ``boost foreground application performance'') or some superior kernel feature that I'm unaware of? 2) FreeBSD has a much faster filesystem (according to my simple tests) than Solaris 2.6 x86. Of course Linux still holds the record for filesystem writes because UFS synchronous metadata writes really slow down filesystem performance. What changes were done to the FreeBSD implementation of UFS to make this possible? is a UFS+ style metadata logging (journaling) feature included? 3) there is an ioctl in SunOS/Solaris to DISABLE synchronous metadata writes (forgot what it is though..) is this supported on FreeBSD? 4) does FreeBSD support LFS (large file summit) considering that UFS files can be >>2GB in size according to the FAQ? or is this just PR (e.g. Linux Reiserfs has 44-bit files, but the libc, etc, don't handle >2GB files) 5) how are pthreads implemented in FreeBSD 3.x? are these repackaged Provenzano's threads, ``real'' kernel threads a la Linux (Linux threads are processes, but fork overhead and ctx switch is very low on Linux as evidenced by lmbench that it doesn't matter too much), or some other form of userspace threads (e.g. FSU threads)? 6) does FreeBSD retain the 4.4BSD/Mach VM system? it certainly consumes much less memory for buffer cache than Linux, at least the stock setup. When I run top(1) there is a parameter called "Wired." Is this the same as wired (nonpageable) memory in the SVR4 VM model? 7) if I want to recompile my kernel and system using PGCC (is this recommended?) which Makefiles do I alter? 8) can I use DMA on IDE drives like Linux does? what sort of I/O does FreeBSD do on the wdc device? is it the dumb PIO that Linux does by default, or is MaxMultsec, etc increased to improve performance? 9) how good is the SMP support in FreeBSD (vis a vis Linux [which is not that good, even in 2.2] and commercial OS's)? 10) when using memfs on /tmp, is space used for files subtracted from swap, like in Solaris 2.x? (e.g. if I fill up /tmp with big files, the system won't be able to swap anymore) 11) I'm still keeping Linux around to run Informix Dynamic Server (as well as the ultra-glitzy Red Hat 6.0 GNOME desktop). Will such a complicated program (IDS) run under emulation? (it uses /etc/shadow instead of /etc/master.passwd, makes extensive use of glibc2 threads, and does many select(4096, ..) in there). 12) how is poll() and select() implemented in the kernel? in the wake of the Mindcraft fiasco much attention has been given to shortcomings in the Linux scheduler (particularly in >2 CPU SMP boxes) and the linear scan necessitated by poll() and select(). How is this issue addressed in BSD? since wcarchive.cdrom.com handles thousands and thousands of clients, this issue must have come up sometime.. also, are ``wake one'' select() semantics implemented? what about sendfile()? 13) (my pet favorite) I like the packaging of Red Hat Linux (it's my other OS) but the inexplicable ``it feels faster'' performance of FreeBSD makes me wonder if anyone has done a ``reverse demon Penguin'' -- Linux userland, FreeBSD kernel. Is this even possible? 14) SGI is releasing XFS under an open-source license. Since XFS is implemented on top of the vnode/vfs system, conceivably all free UNIX variants would benefit. Is it worth it to run BSD on XFS, or is UFS sufficient? I realize these are a lot of questions, but the FAQ does not cover many of them. It's easier to find answers on Linux because you can browse the kernel mailing lists. I was hoping maybe there was a central repository for questions of this nature. ------------------------------------------------------------------- Orlando Andico +63 (2) 937-2293 Mosaic Communications, Inc. +63 (912) 800-8262 Promote bacteria.. it's the only culture some people have. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message