On Tue, Sep 19, 2017 at 01:53:01PM -0600, Jens Axboe wrote: > We've had some issues with writeback in presence of memory reclaim > at Facebook, and this patch set attempts to fix it up. The real > functional change is the last patch in the series, the first 5 are > prep and cleanup patches. > > The basic idea is that we have callers that call > wakeup_flusher_threads() with nr_pages == 0. This means 'writeback > everything'. For memory reclaim situations, we can end up queuing > a TON of these kinds of writeback units. This can cause softlockups > and further memory issues, since we allocate huge amounts of > struct wb_writeback_work to handle this writeback. Handle this > situation more gracefully. This looks nice, but do you have any numbers to show how this improves things? I read the patches, but I'm not strong enough to comment on them at all. But I am interested in how this improves writeback under pressure, if at all. John
