On 7/31/2012 6:55 PM, Jason Newton wrote:
> On Tue, Jul 31, 2012 at 4:46 PM, Stan Hoeppner <stan@xxxxxxxxxxxxxxxxx>wrote:
>> On 7/31/2012 6:01 PM, Jason Newton wrote:
>>> I'm still interested in finding out why streaming a few hundred MB to
>>> has so much over head in comparison to the calculations I do in
>> 1. md eats a lot of cycles at high data rates
> md with intel's raid0? I stopped using linux/softraid, but I've read
> intel's is a mix between hardware and software raid...
Intel Matrix RAID is fakeraid. Designed for consumer workloads. You're
shoving a decidedly non consumer, high b/w IO stream through it. Don't
expect much. In fact I'm surprised you're using consumer grade gear for
this application. You are designing this software/system for a
commercial use case, correct? If so I'd get some better hardware.
CPU overhead for fakeraid will be similar to md/RAID, depending on the
vendor and implementation. In some cases it may be much higher than md.
> 2. ATA overhead
>> 3. IRQ/MSI overhead
>> 4. Etc.
>> All these small bits add up to more than negligible CPU overhead at high
>> data rates.
> Regarding the others, how would I go about measuring their overhead...
To what end?