This won't speed up the actual IO but it should reduce the impact on other work. if you aren't familiar, man sysctl to understand how to apply the below settings. set these 2: vm.dirty_background_bytes = 3000000 vm.dirty_bytes = 5000000 They will be 0 to start with and these 2 settings will be was was used prior to setting bytes: vm.dirty_background_ratio = 0 vm.dirty_ratio = 0 ratio is % of memory. So 16GB * (dirty_ratio - dirty_background_ratio) / write_rate (guess say 50MB, could be 2x either way) and that is how long once you hit dirty_ratio it takes for the IO to unfreeze when you hit dirty_background_ratio. It takes 2-3 seconds to clear 1% on of 16GB so bigger numbers are much worse. I set mine so that really I only have 2MB to clear and that will clear before I notice. And overall about all the big write cache does for you is to give you the false sense with smaller writes that they are done when really they are not. grep -i dirty /proc/meminfo will show you how much you have outstanding, and it will bounce between the 2 settings. On Tue, Mar 23, 2021 at 9:39 AM Richard Shaw <hobbes1069@xxxxxxxxx> wrote: > > I'm getting significant iowait while writing to a 100GB file. I have already made it nocow by copying it to another directory, marking the director nocow (+C) and using cat <oldfile> <newfile> to re-create it from scratch. > > I was under the impression that this should fix the problem. > > On a tangent, it took about 30 minutes to delete the old file... My system is a Ryzen 5 3600 w/ 16GB or memory but it is a spinning disk. I use an NVME for the system and the spinning disk for /home. > > Currently I'm getting random GUI freezes due to the iowait problem and my HDD indicator light basically stays on solid for over an hour now. > > Any tips? > > Thanks, > Richard > _______________________________________________ > users mailing list -- users@xxxxxxxxxxxxxxxxxxxxxxx > To unsubscribe send an email to users-leave@xxxxxxxxxxxxxxxxxxxxxxx > Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ > List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines > List Archives: https://lists.fedoraproject.org/archives/list/users@xxxxxxxxxxxxxxxxxxxxxxx > Do not reply to spam on the list, report it: https://pagure.io/fedora-infrastructure _______________________________________________ users mailing list -- users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to users-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/users@xxxxxxxxxxxxxxxxxxxxxxx Do not reply to spam on the list, report it: https://pagure.io/fedora-infrastructure
