Messages in this thread | | | Date | Thu, 15 Feb 2007 00:33:39 +0000 | From | Alan <> | Subject | Re: [PATCH 9/11] Panic delay fix |
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On Wed, 14 Feb 2007 13:53:08 -0800 Zachary Amsden <zach@vmware.com> wrote:
> > IDE on several platforms has performance critical paths that use > > ndelay(400) or failing that udelay(1) > > Ok, I buy that. A 486DX / 33 Mhz processor takes 10 cycles to issue a > CALL / RET pair. This is about 300ns. Is there an issue with being too > early to issue I/O operations or too late?
Too early you lose, too late you just waste clock time.
> But I fail to see how such careful timing can be done at this > granularity on such hardware without well tweaked assembly code.
Thats what is used most platforms use udelay(1) in fact however - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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