On Mon, Nov 09, 2020 at 01:50:40PM +0000, Trond Myklebust wrote: > On Mon, 2020-11-09 at 09:00 +0100, Peter Zijlstra wrote:
> > I'm thinking the real problem is that you're abusing workqueues. Just > > don't stuff so much work into it that this becomes a problem. Or > > rather, > > if you do, don't lie to it about it. > > If we can't use workqueues to call iput_final() on an inode, then what > is the point of having them at all? Running short stuff, apparently. > Neil's use case is simply a file that has managed to accumulate a > seriously large page cache, and is therefore taking a long time to > complete the call to truncate_inode_pages_final(). Are you saying we > have to allocate a dedicated thread for every case where this happens? I'm not saying anything, but you're trying to wreck the scheduler because of a workqueue 'feature'. The 'new' workqueues limit concurrency by design, if you're then relying on concurrency for things, you're using it wrong. I really don't know what the right answer is here, but I thoroughly hate the one proposed.
