Hello, Ian. On Wed, Jun 17, 2020 at 03:37:43PM +0800, Ian Kent wrote: > The series here tries to reduce the locking needed during path walks > based on the assumption that there are many path walks with a fairly > large portion of those for non-existent paths, as described above. > > That was done by adding kernfs negative dentry caching (non-existent > paths) to avoid continual alloc/free cycle of dentries and a read/write > semaphore introduced to increase kernfs concurrency during path walks. > > With these changes we still need kernel parameters of udev.children-max=2048 > and systemd.default_timeout_start_sec=300 for the fastest boot times of > under 5 minutes. I don't have strong objections to the series but the rationales don't seem particularly strong. It's solving a suspected problem but only half way. It isn't clear whether this can be the long term solution for the problem machine and whether it will benefit anyone else in a meaningful way either. I think Greg already asked this but how are the 100,000+ memory objects used? Is that justified in the first place? Thanks. -- tejun
