Hi, On 23/03/17 19:32, Byungchul Park wrote: > cpudl_find() is used to find a cpu having the latest dl. The function > should return the latest cpu among ones satisfying task's affinity and > dl constraint, but current code gives up immediately and just return > fail when it fails at the test *only with* the maximum cpu. > > For example: > > cpu 0 is running a task (dl: 10). > cpu 1 is running a task (dl: 9). > cpu 2 is running a task (dl: 8). > cpu 3 is running a task (dl: 2). > > where cpu 3 want to push a task (affinity is 1 2 3 and dl is 1).
Hummm, but this should only happen if you disable admission control, right? Otherwise task's affinity can't be smaller that 0-3. > > In this case, the task should be migrated from cpu 3 to cpu 1, and > preempt cpu 1's task. However, current code just returns fail because > it fails at the affinity test with the maximum cpu, that is, cpu 0. > > This patch set tries to find the best among ones satisfying task's > affinity and dl constraint until success or no more to see. > Anyway, do you have numbers showing how common is you fail scenario? It would be interesting to understand how much the slow path is actually used, IMHO. Thanks, - Juri
