Hi, I just completed some rough tests on a pretty small LPAR (just 1.,5GB RAM) and I ran the GA kernel 4.15 as well as the HWE kernel 5.0.
An activation of another DASD device requires on kernel 5.0 about 90% less memory compared to kernel 4.15 - so there is indeed a big difference. However, with the 20 DASDs that I had left for the test I wasn't able to run in an OOM situation, but the memory left decreased consistently... So picking up (means SRU-ing : https://wiki.ubuntu.com/StableReleaseUpdates) the patch mentioned above seems to be reasonable We're discussing the SRU of it right now (a quick cherrypick didn't worked cleanly, so a backport is needed). In between I recommend (and +1 with Christian) to use the HWE kernel instead (latest is 5.0 - shipped with the regular 18.04.3 image). There is an alternate installer based on the HWE kernel in boot-hwe of the image (instead you want/need the fix already during install) and a package in the archives (named: linux-generic-hwe-18.04) and it is supported. Hence I think it's a better alternative compared to a kernel 4.18. So in case you do not have any hard requirements for using 4.15, you can just install the HWE kernel: "linux-generic-hwe-18.04" Please notice that you do not have to reinstall 18.04 - just keep your existing system up to date and run: sudo apt update && sudo apt full-upgrade sudo apt install linux-generic-hwe-18.04 Once the SRU was completed and an updated 4.15 was rolled out, you can always go back to the GA kernel. Berry, may I ask how big the system is that you are using (regading RAM)? Must be pretty small - just notice that it's recommended to use 1GB RAM (or more): https://help.ubuntu.com/18.04/installation-guide/s390x/ch03s05.html (and even this is a theoretical number, in practise you would define much more - depending on your use case). Bye, Frank On Mon, Nov 11, 2019 at 2:39 PM van Sleeuwen, Berry < [email protected]> wrote: > Hi Stefan, > > I have installed the 4.18 kernel and I can confirm that this indeed solves > the issue. When I enable the disks the memory usage is much lower now. > > Thanks. > > Met vriendelijke groet/With kind regards/Mit freundlichen Grüßen, > Berry van Sleeuwen > Flight Forum 3000 5657 EW Eindhoven > > -----Original Message----- > From: Linux on 390 Port <[email protected]> On Behalf Of Stefan > Haberland > Sent: Friday, November 08, 2019 4:11 PM > To: [email protected] > Subject: Re: Ubuntu 18-04 unable to add DASD > > > commit 3284da34a87a ("s390/dasd: reduce the default queue depth and nr of > hardware queues") > > which is available since kernel 4.18. This is should be available in > Ubuntu 18.04.2 as far as I know. > So if you are using 18.04(.1) with kernel 4.15 this might be a problem and > I would suggest to upgrade to 18.04.2 with kernel 4.18 or later. > > Regards, > Stefan > > This e-mail and the documents attached are confidential and intended > solely for the addressee; it may also be privileged. If you receive this > e-mail in error, please notify the sender immediately and destroy it. As > its integrity cannot be secured on the Internet, Atos’ liability cannot be > triggered for the message content. Although the sender endeavours to > maintain a computer virus-free network, the sender does not warrant that > this transmission is virus-free and will not be liable for any damages > resulting from any virus transmitted. On all offers and agreements under > which Atos Nederland B.V. supplies goods and/or services of whatever > nature, the Terms of Delivery from Atos Nederland B.V. exclusively apply. > The Terms of Delivery shall be promptly submitted to you on your request. > > ---------------------------------------------------------------------- > For LINUX-390 subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO LINUX-390 or > visit > http://www2.marist.edu/htbin/wlvindex?LINUX-390 > ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO LINUX-390 or visit http://www2.marist.edu/htbin/wlvindex?LINUX-390
