Date: Tue, 12 Feb 2008 10:53:39 +0100 From: Dominic Fandrey <kamikaze@bsdforen.de> To: Tom Evans <tevans.uk@googlemail.com> Cc: "Carlos A. M. dos Santos" <unixmania@gmail.com>, freebsd-stable@freebsd.org Subject: Re: RELENG_7: interrupt eating whole cpu core Message-ID: <47B16CA3.5070700@bsdforen.de> In-Reply-To: <1202808057.2126.45.camel@localhost> References: <47A9F835.1060200@bsdforen.de> <47AA0696.5020109@bsdforen.de> <7872AB6E-21DA-4E2D-93C0-D07CFA3A7E47@mac.com> <47AA0E3E.4020304@bsdforen.de> <e71790db0802071822l661bdcb8s6dfe5b94be11f0dc@mail.gmail.com> <47ABF66E.4040807@bsdforen.de> <e71790db0802080543g54d27bb8nfdc33e342f982b4@mail.gmail.com> <1202485501.2126.34.camel@localhost> <47AC7FF6.1020801@bsdforen.de> <1202491071.2126.42.camel@localhost> <47ACA0E4.2030905@bsdforen.de> <1202808057.2126.45.camel@localhost>
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Tom Evans wrote: > On Fri, 2008-02-08 at 19:35 +0100, Dominic Fandrey wrote: >> Tom Evans wrote: >>> On Fri, 2008-02-08 at 17:14 +0100, Dominic Fandrey wrote: >>>> Tom Evans wrote: >>>>> If I try to turn on DMA, I just get WDMA2, which just doesn't cut it: >>>> I think any DMA mode is fast enough to handle a DVD drive. There's just no >>>> necessity for more. >>>> >>> WDMA is not UDMA. Any UDMA variant would be enough. WDMA2 provides a >>> maximum of 16MiB/s, which will frequently lead to buffer underruns >>> viewing a DVD. UDMA2 provides a maximum of 33MiB/s, which IS plenty. >> 16MB/s is exactly what is needed for 12x DVD access. I think this is the usual >> speed for a Notebook drive nowadays and it suffices for me. >> >>>>>> # atacontrol mode acd0 udma5 >>>>> current mode = WDMA2 >>>> Same as for me. I'm satisfied with the speed of the drive. >>> I'm rarely satisfied - I'm quite often not bothered enough to pursue :) >> Well, if 12x speed is not enough for you, you have to use an external drive. >> This is not a driver issue. It's just what your drive supports. > > The chipset supports UDMA6, the drive supports UDMA6, I should be happy > with WDMA2 because 'thats what works'? Thanks for your 'help'. I'll > continue on here from myself. I don't know which drive you are using, but mine even only supports 8xDVD-reading so the highest transfer rate is 9.9606 MB/s. There's no way a faster mode would improve anything.
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