Date: Sun, 9 Dec 2012 12:33:16 +0000 From: "b.f." <bf1783@googlemail.com> To: Adrian Chadd <adrian@freebsd.org>, freebsd-hackers@freebsd.org Subject: Re: FreeBSD for serious performance? Message-ID: <CAGFTUwOB6TdCJFoA1B4Q6TD1RyQqtLXRoW7CuqRCj3m7PG%2Bq7g@mail.gmail.com>
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>Right, so the bug here is "why isn't atacam attaching to the nforce4 >ultra chipset." > >So this has changed from "FreeBSD doesn't do NCQ" to "FreeBSD doesn't >do NCQ on my particular desktop-aimed motherboard chipset." They're >slightly different in scope, wouldn't you agree? >Please file a PR and see if that can get resolved. I personally have >no idea about the storage side of things so I don't know if it's a >device id or whether there's something more complicated than that. Both the old and the new ata(4) have basic support for most of the older Nvidia chipsets, but lack some SATA-specific features like NCQ. Before AHCI was widely adopted, there were a variety of different interfaces on early SATA controllers. When Alexander and Scott were rewriting parts of the ATA and CAM code in FreeBSD, they had a limited amount of time and resources, so they concentrated on the newer ahci(4), mvs(4), and siis(4), not the many different interfaces of the earlier SATA controllers, although they invited people to add some of these on their own. The situation is also complicated by the fact that some of these earlier controllers had bugs, so even in Linux, where a larger number of the earlier controllers are more fully supported, some of the drivers disable NCQ and some other features by default, although the controllers are supposed to support them, e.g.: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=e2e031eb09760c36099ac127eeb175e06d257aef Of course, it is now possible to buy relatively inexpensive add-in SATA controller cards that are fully supported by one of the newer drivers and perform better than most of the old controllers. b.
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