Control: severity -1 serious On Sun, Oct 04, 2026 at 12:38:34PM +0200, Aurelien Jarno wrote: > Source: vtk9 > Version: 9.6.2+ds-1 > Severity: normal
I'm raising the severity to serious: This change has increased the build time on the slower riscv64 buildds from 4 days to 6 days, it has to be reverted. > Hi, > > Starting with vtk9 9.6.2+ds-1, the package use guess-concurrency to > limit parallel workers, which is a good move. However on some build > daemons, it significantly increased the build time. > > One of the reason is bug#1149922. The other reason is that hardware or > VMs usually use an integer number of GiB for the RAM (and often a power > of 2). There is always a bit of RAM lost (kernel code or data, reserved > memory, ...) and this is enough to get just below the 4G per core. > > Would you consider reducing the required memory to 3.8G (guess-concurrency > accepts > floating numbers) to account for that? Given the near-perfect scaling of a 2.76x build time increase on the same i386 buildd where this guess-concurrency use reduced the number of cores used by a factor of 3, even 2G would likely still harm build time on some architectures. It is harmful to use guess-concurrency unless: 1. it is fixing an actual problem that has been observed, and 2. the numbers have been properly measured and not just guessed The only good option is to drop this bogus usage of guess-concurrency in vtk9, there is no visible reason why it was added at all and adding it with guessed numbers is just harmful. > Thanks > Aurelien cu Adrian
