Hi Wolfram-san again, > From: Yoshihiro Shimoda, Sent: Tuesday, May 7, 2019 5:59 PM > > 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). I have measured them + IOMMU enabled environment. It seems my guess is correct. - 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). - case 3: usb 3.0 host + usb SSD as SuperSpeed (IOMMU is enabled). - case 4: usb 3.0 host + usb SSD via a usb2.0 hub as high-speed (IOMMU is enabled). --- kernel v5.1-rc7 + local patches + USB SSD ext4 format,,,,,,,,,,,,,,,,,,,,,,,,,, Buildroot 2019.02.1,,,,,,,,,,,,,,,,,,,,,,,,,, Bonnie++ 1.03e : bonnie\+\+ -d ./ -s 8192 -r 4096 -b -u root,,,,,,,,,,,,,,,,,,,,,,,,,, ,,,,,,,,,,,,,,,,,,,,,,,,,, environment,Size,Sequential Output - per char (K/sec),<- (CPU %),Sequential Output - block (K/sec),<- (CPU %),Sequential Output - rewrite (K/sec),<- (CPU %),Sequential Input - per char (K/sec),<- (CPU %),Sequential Input ? block (K/sec),<- (CPU %),Random seeks,<- (CPU %),files,Sequential Create,<- (CPU %),Sequential Read,<- (CPU %),Sequential Delete,<- (CPU %),Random Create,<- (CPU %),Random Read,<- (CPU %),Random Delete,<- (CPU %) H3_SuperSpeed_No_IOMMU,8G,82598,99,242161,58,102489,25,73719,98,254089,32,2133.3,6,16,382,2,+++++,+++,385,1,380,1,+++++,+++,387,2 H3_HighSpeed_No_IOMMU,8G,41971,53,39983,9,16459,4,37900,51,37833,5,1585.7,5,16,304,1,+++++,+++,295,1,302,1,+++++,+++,294,1 H3_SuperSpeed_IOMMU,8G,66139,99,276686,65,132297,33,69732,99,293396,37,2099.2,7,16,389,2,+++++,+++,391,1,382,1,+++++,+++,391,2 H3_HighSpeed_IOMMU,8G,43191,50,40446,9,17432,4,38541,51,38481,5,1619.4,4,16,302,1,+++++,+++,296,1,303,1,+++++,+++,294,1 --- Best regards, Yoshihiro Shimoda
