On Wed, Oct 24, 2018 at 04:11:24PM +0530, Srikar Dronamraju wrote: > * Peter Zijlstra <[email protected]> [2018-10-24 12:15:08]: > > > On Wed, Oct 24, 2018 at 03:16:46PM +0530, Srikar Dronamraju wrote: > > > * Mel Gorman <[email protected]> [2018-10-24 09:56:36]: > > > > > > > On Wed, Oct 24, 2018 at 08:32:49AM +0530, Srikar Dronamraju wrote: > > > > It would certainly be a bit odd because the > > > > application is asking for some protection but no guarantees are given > > > > and the application is not made aware via an error code that there is a > > > > problem. Asking the application to parse dmesg hoping to find the right > > > > error message is going to be fragile. > > > > > > Its a actually a good question. > > > What should we be doing if a mix of isolcpus and housekeeping (aka > > > non-isolcpus) is given in the mask. > > > > > > Right now as you pointed, there is no easy way for the application to know > > > which are the non-isolcpus to set its affinity. cpusets effective_cpus and > > > cpus_allowed both will contain isolcpus too. > > > > The easy option is to not use isolcpus :-) It is a horrifically bad > > interface. > > Agree, but thats something thats been exposed long time back. > Do we have an option to remove that? Hopefully nobody is using it. >
I occasionally see bugs asking questions about interference from the kernel when isolcpus are in use. The last one was related to a timer interrupt every HZ (not a mainline kernel) but still, it's some evidence that it has users :( -- Mel Gorman SUSE Labs
