[Bug 1880943] Re: [focal] disk I/O performance regression
If ext4lazyinit isn't in used, do we still see the performance regression? -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1880943 Title: [focal] disk I/O performance regression To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1880943/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1880943] Re: [focal] disk I/O performance regression
Playing around with the now available IO schedulers does not appear to help much and looking at iotop while the test runs does show ext4lazyinit consuming much of the IO most of the time while the test runs. I wonder if this is a more ominous change of behavior after all Total DISK READ: 0.00 B/s | Total DISK WRITE: 0.00 B/s Current DISK READ: 0.00 B/s | Current DISK WRITE: 22.22 M/s TID PRIO USER DISK READ DISK WRITE SWAPIN IO>COMMAND 948 be/4 root0.00 B/s0.00 B/s 0.00 % 99.99 % [ext4lazyinit] 5651 be/4 root0.00 B/s0.00 B/s 0.00 % 99.99 % fio /usr~write.fio 22 be/4 root0.00 B/s0.00 B/s 0.00 % 94.61 % [kworker~-252:384] Reopening to get some take from kernel team on the change of IO schedulers and if this is an anticipated side effect and/or if any known regression surrounding the ext4lazyinit process. ** Changed in: linux (Ubuntu) Status: Invalid => New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1880943 Title: [focal] disk I/O performance regression To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1880943/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1880943] Re: [focal] disk I/O performance regression
We have been using the ext4lazyinit for quite some time, so I guess this must be a combination of multiple things. I see that the 5.4 kernel brings a change of io scheduler to mq- deadline. Could the combination of ext4lazyinit+mq-deadline+rotational drives be a problem? -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1880943 Title: [focal] disk I/O performance regression To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1880943/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1880943] Re: [focal] disk I/O performance regression
For any future travelers this issue was caused by the much debated ext4lazyinit "feature". # iotop Total DISK READ: 0.00 B/s | Total DISK WRITE: 0.00 B/s Current DISK READ: 0.00 B/s | Current DISK WRITE: 7.38 M/s TID PRIO USER DISK READ DISK WRITE SWAPIN IO>COMMAND 947 be/4 root0.00 B/s0.00 B/s 0.00 % 2.96 % [ext4lazyinit] While it on paper is accounting for a small percentage of the IO it will incur a noticeable performance hit to the system until it is done. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1880943 Title: [focal] disk I/O performance regression To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1880943/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1880943] Re: [focal] disk I/O performance regression
That is an excellent idea. Before embarking on that endeavor I did a last control test which involved deploying Bionic and then installing the Focal 5.4 kernel packages, and lo and behold the system is still performant. Redeploying Focal (with the Focal kernel obviously) makes it non- performant again. While still baffled by the roots of the issue I will mark this bug Invalid for the kernel packages for now as there is obviously some mischief somewhere else involved in the end result. Depending on what I find the open status may or may not return. Thank you for your support so far. ** Changed in: linux (Ubuntu) Status: Confirmed => Invalid -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1880943 Title: [focal] disk I/O performance regression To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1880943/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1880943] Re: [focal] disk I/O performance regression
Would it be possible for you to do a kernel bisection? First, find the last -rc kernel works and the first -rc kernel doesn’t work from http://kernel.ubuntu.com/~kernel-ppa/mainline/ Then, $ sudo apt build-dep linux $ git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git $ cd linux $ git bisect start $ git bisect good $(the working version you found) $ git bisect bad $(the non-working version found) $ make localmodconfig $ make -j`nproc` deb-pkg Install the newly built kernel, then reboot with it. If it still have the same issue, $ git bisect bad Otherwise, $ git bisect good Repeat to "make -j`nproc` deb-pkg" until you find the offending commit. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1880943 Title: [focal] disk I/O performance regression To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1880943/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1880943] Re: [focal] disk I/O performance regression
Thank you for the suggestion to test mainline. Regarding the kernel parameters: The test is run on the host and not in a virtual machine, for completeness I have removed the iommu and vf related kernel parameters and they do not affect the outcome of the test. Unfortunately using the mainline kernel does not appear to help on the machines in question: # cat /proc/cmdline BOOT_IMAGE=/vmlinuz-5.7.0-050700rc7-generic root=UUID=99527048-4021-4a56-a7d3-21c6cb761879 ro # uname -a Linux node-mees 5.7.0-050700rc7-generic #202005242331 SMP Sun May 24 23:33:19 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux # cpufreq-info -o ... CPU 47 120 kHz ( 41 %) -290 kHz (100 %) - performance # fio /usr/share/doc/fio/examples/fio-seq-write.fio ... Run status group 0 (all jobs): WRITE: bw=63.1MiB/s (66.2MB/s), 63.1MiB/s-63.1MiB/s (66.2MB/s-66.2MB/s), io=60.0GiB (64.4GB), run=973234-973234msec ** Changed in: linux (Ubuntu) Status: Incomplete => New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1880943 Title: [focal] disk I/O performance regression To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1880943/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1880943] Re: [focal] disk I/O performance regression
Note that I didn't add any kernel parameter, so my first guess would be "iommu=pt" doesn't get passthrough right. ** Changed in: linux (Ubuntu) Status: Confirmed => Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1880943 Title: [focal] disk I/O performance regression To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1880943/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1880943] Re: [focal] disk I/O performance regression
Tried 4.15.0-102, 5.4.0-33 and mailing kernel all three show similar performance (~2100MB/s). Please test latest mainline kernel: https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.7-rc7/ And decide what's the next step based on the performance of mainline kernel. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1880943 Title: [focal] disk I/O performance regression To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1880943/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1880943] Re: [focal] disk I/O performance regression
Note that to rule out any hardware configuration/malfunction issue between the two hosts I have re-run the tests on the exact same machine used for the non-performant Focal tests with good performance for Bionic. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1880943 Title: [focal] disk I/O performance regression To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1880943/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1880943] Re: [focal] disk I/O performance regression
** Tags added: uosci -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1880943 Title: [focal] disk I/O performance regression To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1880943/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
