Public bug reported: Hi!
I've noticed that the disk I/O performance has dropped in the 4.15 series (Ubuntu 16.04 HWE), at least on mechanical hard drives; I'm working on an early Thinkpad T410s with 4Gb of RAM and a 1.8" 250Gb microSATA Toshiba hard drive. Both 4.4 (lts-xenial) and 4.18 (liquorix) series are better performing than the 4.15 series, which shows a lot of r/w activity during application startup in comparison to the aforementioned kernels. I've run some primitive benchmarks on all 3 kernel series, 3 passes each, showing the following average rates: # Kernel 4.15.0-34 ## I/O Scheduler: [deadline] ### $ time sh -c "dd if=/dev/zero of=testfile bs=1024k count=1k && sync && rm -f testfile" 1024+0 registros leídos 1024+0 registros escritos 1073741824 bytes (1,1 GB, 1,0 GiB) copied, 29,1757 s, 36,8 MB/s sh -c 0,01s user 1,33s system 4% cpu 31,724 total # Kernel 4.18-liquorix (https://liquorix.net) ## I/O Scheduler: [deadline] ### time sh -c "dd if=/dev/zero of=testfile bs=1024k count=1k && sync && rm -f testfile" 1024+0 registros leídos 1024+0 registros escritos 1073741824 bytes (1,1 GB, 1,0 GiB) copied, 23,7735 s, 45,2 MB/s sh -c 0,15s user 1,25s system 4% cpu 28,193 total # Kernel 4.4 lts-xenial ## I/O Scheduler: [deadline] ### $ time sh -c "dd if=/dev/zero of=testfile bs=1024k count=1k && sync && rm -f testfile" 1024+0 registros leídos 1024+0 registros escritos 1073741824 bytes (1,1 GB, 1,0 GiB) copied, 23,9265 s, 44,9 MB/s sh -c 0,00s user 1,68s system 5% cpu 32,312 total As you can see, disk I/O is quite similar on both 4.4 and 4.18 series, but drops over a 25% on kernel 4.15. It may not be noticeable on a modern machine with SSD drives, but it's quite a drag on mechanical drives. Even opening Emacs+Spacemacs takes over a minute under kernel 4.15, in contrast to the 20+ seconds under kernels 4.4 and 4.18-liquorix. What further information would you need from me to pinpoint probable bottlenecks? ProblemType: Bug DistroRelease: elementary 0.4.1 Package: linux-image-4.15.0-34-generic 4.15.0-34.37~16.04.1 [origin: Ubuntu] Uname: Linux 4.18.0-8.1-liquorix-amd64 x86_64 NonfreeKernelModules: nvidia_uvm nvidia wl ApportVersion: 2.20.1-0ubuntu2.18 Architecture: amd64 CurrentDesktop: Pantheon Date: Mon Sep 17 16:43:06 2018 InstallationDate: Installed on 2017-09-24 (358 days ago) InstallationMedia: elementary OS 0.4.1 "Loki" - Stable amd64 (20170814) SourcePackage: linux-signed-hwe UpgradeStatus: No upgrade log present (probably fresh install) ** Affects: linux-signed-hwe (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug loki third-party-packages -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1793013 Title: Poor hard disk performance under kernel 4.15 series (HWE stack) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-signed-hwe/+bug/1793013/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
