Gregory Price <gourry@xxxxxxxxxx> writes: > On Sat, Dec 21, 2024 at 01:57:58PM +0800, Huang, Ying wrote: >> Hi, Joshua, >> >> Joshua Hahn <joshua.hahnjy@xxxxxxxxx> writes: >> >> > On Fri, 13 Dec 2024 15:19:20 +0900 Hyeonggon Yoo <hyeonggon.yoo@xxxxxx> wrote: >> > >> >> On 2024-12-11 06:54 AM, Joshua Hahn wrote: >> [snip] > >> > >> > Regardless of what implementation makes sense, I can re-write the >> > description so that there is no ambiguity when it comes to the >> > expected behavior of the code. Thank you for pointing this out! >> >> I don't think that it's a good idea to override the user supplied >> configuration values. User configurations always have higher priority >> than system default configurations. IIUC, this is the general rule of >> Linux kernel user space interface. >> > > We discussed this and decided it was confusing no matter what we did. > > If new data comes in (CDAT data from a hotplug event), then the weights > are now wrong for the new global state - regardless of whether the user > set a weight manually or not. This also allowed us to simplify the > implementation a bit. > > But if generally we need to preserve user settings, then I think the > best we can do to provide a sane system is ignore the user setting when > re-weighting on a hotplug event. > > e.g. user has not set a value > > default_values [5,2,-] <- 1 node not set, expected to be hotplugged > user_values [-,-,-] <- user has not set values > effective [5,2,-] > > hotplug event > default_values [2,1,1] - reweight has occurred > user_values [-,-,-] > effective [2,1,1] > > e.g. user has set a value > > default_values [5,2,-] <- 1 node not set, expected to be hotplugged > user_values [4,-,-] <- user has only set one value > effective [4,2,-] > > hotplug event > default_values [2,1,1] - reweight has occurred > user_values [4,-,-] > effective [4,1,1] Another choice is that if the user set a value, he/she set all values effectively. Even if he/she doesn't set the other values, he/she thinks that the other values are good, and more importantly, the ratio is good. If so, default_values [5,2,-] <- 1 node not set, expected to be hotplugged user_values [4,2,0] <- user has only set one value, not populated nodes have value 0 effective [4,2,0] hotplug event default_values [2,1,1] - reweight has occurred user_values [4,2,0] effective [4,2,0] In this way, 0 becomes a valid value too. What do you think about this? > So default values get updated, but user values get left alone. > > If that's sane we'll fix it up. --- Best Regards, Huang, Ying
