On 26.07.22 17:54, Stefan Wahren wrote: > Hi Ojaswin, > > Am 26.07.22 um 08:43 schrieb Ojaswin Mujoo: >> 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. >> > I run the firmware update 5 times with mb_optimize_scan=0 on my > Raspberry Pi 4 and the industrial SD card and everytime the update worked. >> [CCing Jan] FYI, Jan yesterday reported benchmark regresses that might or might not be related Stefan's regression on the Raspberry Pi: https://lore.kernel.org/all/20220727105123.ckwrhbilzrxqpt24@quack3/ Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat) P.S.: As the Linux kernel's regression tracker I deal with a lot of reports and sometimes miss something important when writing mails like this. If that's the case here, don't hesitate to tell me in a public reply, it's in everyone's interest to set the public record straight. #regzbot monitor https://lore.kernel.org/all/20220727105123.ckwrhbilzrxqpt24@quack3/
