Hi Wolfram-san, > From: Wolfram Sang, Sent: Friday, April 26, 2019 6:46 PM > > Hi Shimoda-san, > > thanks for working on this! > > > Please refer to the end of this email about the performance. > > Yes, nice improvements, great! Thanks! > > (I beleive if the performance is improved, the CPU load is also increased.) > > I do wonder about this a bit, though. IPMMU and DMA shouldn't be that > much expensive for the CPU, or? Am I overlooking something? I'm guessing that a user land app (in this case bonnie++) consumes CPU load for some reason. I'll experiment whether my guess is correct or not by using usb 3.0 host like below tomorrow: - case 1: usb 3.0 host + usb SSD as SuperSpeed (IOMMU is disabled). - case 2: usb 3.0 host + usb SSD via a usb2.0 hub as high-speed (IOMMU is disabled). Best regards, Yoshihiro Shimoda > Kind regards, > > Wolfram
