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 >> disk >>> has so much over head in comparison to the calculations I do in >> userspace, >> >> 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? -- Stan _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
