On Mon, Jul 25, 2022 at 09:09:32PM +0200, Stefan Wahren wrote: > Hi Ojaswin, > > Am 25.07.22 um 17:07 schrieb Ojaswin Mujoo: > > On Mon, Jul 18, 2022 at 03:29:47PM +0200, Stefan Wahren wrote: > > > Hi, > > > > > > i noticed that since Linux 5.18 (Linux 5.19-rc6 is still affected) i'm > > > unable to run "rpi-update" without massive performance regression on my > > > Raspberry Pi 4 (multi_v7_defconfig + CONFIG_ARM_LPAE). Using Linux 5.17 this > > > tool successfully downloads the latest firmware (> 100 MB) on my development > > > micro SD card (Kingston 16 GB Industrial) with a ext4 filesystem within ~ 1 > > > min. The same scenario on Linux 5.18 shows the following symptoms: > > > > > > - download takes endlessly much time and leads to an abort by userspace in > > > most cases because of the poor performance > > > - massive system load during download even after download has been aborted > > > (heartbeat LED goes wild) > > > - whole system becomes nearly unresponsive > > > - system load goes back to normal after > 10 min > > > - dmesg doesn't show anything suspicious > > > > > > I was able to bisect this issue: > > > > > > ff042f4a9b050895a42cae893cc01fa2ca81b95c good > > > 4b0986a3613c92f4ec1bdc7f60ec66fea135991f bad > > > 25fd2d41b505d0640bdfe67aa77c549de2d3c18a bad > > > b4bc93bd76d4da32600795cd323c971f00a2e788 bad > > > 3fe2f7446f1e029b220f7f650df6d138f91651f2 bad > > > b080cee72ef355669cbc52ff55dc513d37433600 good > > > ad9c6ee642a61adae93dfa35582b5af16dc5173a good > > > 9b03992f0c88baef524842e411fbdc147780dd5d bad > > > aab4ed5816acc0af8cce2680880419cd64982b1d good > > > 14705fda8f6273501930dfe1d679ad4bec209f52 good > > > 5c93e8ecd5bd3bfdee013b6da0850357eb6ca4d8 good > > > 8cb5a30372ef5cf2b1d258fce1711d80f834740a bad > > > 077d0c2c78df6f7260cdd015a991327efa44d8ad bad > > > cc5095747edfb054ca2068d01af20be3fcc3634f good > > > 27b38686a3bb601db48901dbc4e2fc5d77ffa2c1 good > > > > > > commit 077d0c2c78df6f7260cdd015a991327efa44d8ad > > > Author: Ojaswin Mujoo <ojaswin@xxxxxxxxxxxxx> > > > Date: Tue Mar 8 15:22:01 2022 +0530 > > > > > > ext4: make mb_optimize_scan performance mount option work with extents > > > > > > If i revert this commit with Linux 5.19-rc6 the performance regression > > > disappears. > > > > > > Please ask if you need more information. > > Hi Stefan, > > > > Apologies, I had missed this email initially. So this particular patch > > simply changed a typo in an if condition which was preventing the > > mb_optimize_scan option to be enabled correctly (This feature was > > introduced in the following commit [1]). I think with the > > mb_optimize_scan now working, it is somehow causing the firmware > > download/update to take a longer time. > > > > I'll try to investigate this and get back with my findings. > > thanks. I wasn't able to reproduce this heavy load symptoms with every SD > card. Maybe this depends on the write performance of the SD card to trigger > the situation (used command to measure write performance: dd if=/dev/zero > of=/boot/test bs=1M count=30 oflag=dsync,direct ). > > I tested a Kingston consumer 32 GB which had nearly constant write > performance of 13 MB/s and didn't had the heavy load symptoms. The firmware > update was done in a few seconds, so hard to say that at least the > performance regression is reproducible. > > I also tested 2x Kingston industrial 16 GB which had a floating write > performance between 5 and 10 MB/s (wear leveling?) and both had the heavy > load symptoms. > > All SD cards has been detected as ultra high speed DDR50 by the emmc2 > interface. > > Best regards > > > > > Regard, > > Ojaswin > > > > [1] > > commit 196e402adf2e4cd66f101923409f1970ec5f1af3 > > From: Harshad Shirwadkar <harshadshirwadkar@xxxxxxxxx> > > Date: Thu, 1 Apr 2021 10:21:27 -0700 > > > > ext4: improve cr 0 / cr 1 group scanning > > > > > Regards > > > Thanks for the info Stefan, I'm still trying to reproduce the issue but it's slightly challenging since I don't have my RPi handy at the moment. In the meantime, would you please try out the mb_optmize_scan=0 command line options to see if that helps bypass the issue. This will help confirm if the issue lies in mb_optmize_scan itself or if its something else. You can perhaps mount the root file system with this option using the following kernel command line argument rootflags="mb_optimize_scan=0" You can also confirm if mb_optimize_scan was turned off by checking the first line in output of: cat /proc/fs/ext4/<dev>/mb_structs_summary Regards, Ojaswin
