On Sat 12-09-20 17:32:41, Rogério Brito wrote: > Now, to the subject: is this that you describe (RCU or VFS), in some sense, > related to, say, copying a "big" file (e.g., a movie) to a "slow" media (in > my case, a USB thumb drive, so that I can watch said movie on my TV)? > > I've seen backtraces mentioning "task xxx hung for yyy seconds" and a > non-reponsive cp process at that... I say RCU or VFS because I see this > with the thumb drives with vfat filesystems (so, it wouldn't be quite > related to ext4, apart from the fact that all my Linux-specific > filesystems are ext4). This is very likely completely different problem. I'd need to see exact messages and kernel traces but usually errors like these happen when the IO is very slow and other things (such as grabbing some locks or doing memory allocation) get blocked waiting for that IO. In the case Linus speaks about this is really more about CPU bound tasks that heavily hammer the same cached contents. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
