Date: Tue, 11 Dec 2012 15:43:21 -0500 From: "Dieter BSD" <dieterbsd@engineer.com> To: freebsd-hackers@freebsd.org Subject: Re: FreeBSD for serious performance? Message-ID: <20121211204323.310760@gmx.com>
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>>Ronald writes: >>> the last Alpha to be produced was shipped way back in 2004... eight years >>> ago... with a top speed of 1.3 GHz I now have a cheap little media player >>> thingy sitting on my desk, and _each_ of its two cores runs faster than tha\ t. >>> In short, Alphas hardly constitute high-end hardware in this day and age. >> >> So clock rate is the only thing that matters in your world? > > Yea, pretty much. > > As regards to reliability, except for the occasional low-level quirk (which > is usually taken care of for me by the kernel guys) I've never had a processo\ r > fail on me. Once, about five or six years ago I accidentally burnt up an > Athlon XP (by not having the heatsink properly seated) but that was entirely > my fault. I care about data integrity, so things like ECC are on my must-have list. I suspect that your "cheap little media player thingy" doesn't have ECC. If you don't care about getting the correct answer you can have infinite speed. A high clock rate doesn't help when some device driver does block_all_interrupts(); while(1) DELAY(MIGHT_AS_WELL_BE_FOREVER); At least four device drivers have caused me to lose data this way. Not what I call high performance. >> In my world, high-end means high quality. It doesn't necessarily >> mean fast, or recent. Data integrity, and yes, reliability, that sort of thing. Performance-wise, in most cases I don't expect to get 99.9999% of the theoretical best case, I'm usually happy with 90-95%. But without NCQ I'm only getting ~6% of what I should be getting. Pretty pathetic for an OS that claims to be all about performance. All the more so when the crappy OSes do support NCQ on that chip. It's not some rare, obscure chip. Lots of boxes have it. >> I never found a way to boot from different partitions, much less >> different disks with GPT. > > Having just been recently convinced to switch over to GPT (from MBR) I do > most sincerly hope that you are either joking or mistaken about this. I am neither joking nor mistaken. I looked but could not find a way. I am not claiming that a way does not exist, merely that I couldn't find it. Perhaps there wasn't a way when I looked (it was awhile ago) but does exist now? I have never been a fan of MBRs, they are for pee-cees with the expected ugly kludges and limitations, real machines don't use them. GPT isn't perfect, but it seems much nicer than MBRs. Warren writes: > Grub (or grub2) can do it. Back when I was triple-booting FreeBSD, NetBSD and Linux I used grub (rev number forgotten). It was supposed to be able to boot BSD from a partition but I never got that to work. I had to have it boot the MBR of a different disk which then booted BSD. I wrote 3 little shell scripts that edited grub's menu to change the default. So I could be running FreeBSD and type "boot_netbsd", and go have lunch while it rebooted. Other than not booting BSD from a partition it wasn't that bad for something that smells of penguin. > If you're booting multiple versions of FreeBSD, see gpart(8) > for some partition attributes that may help. You mean the bootme bootonce stuff? That looks promising, assuming I can manage to decode the man page, and figure out what it actually does. Mostly multiple versions of FreeBSD. (for example 7.0 had a couple of bugs preventing it from booting, so having 6 still available was essential.) I no long need Linux (YEA!!!), and after a certain fubar incident have declared a Linux Free Zone. It would be nice if I could also boot Net/Open/Dragonfly. I don't see a way to boot multiple disks, but GPT allows enough partitions that I probably won't care. Not sure if the bootme bootonce stuff wasn't there yet when I looked, or if I just missed it. Thanks for the pointer. > Or even consider ZFS boot environments. I plan to stick with FFS w/softdeps.
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