On 9/20/19 5:10 PM, Linus Torvalds wrote: > On Fri, Sep 20, 2019 at 4:05 PM Linus Torvalds > <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: >> >> >> Now, I hear you say "those are so small these days that it doesn't >> matter". And maybe you're right. But particularly for slow media, >> triggering good streaming write behavior has been a problem in the >> past. > > Which reminds me: the writebehind trigger should likely be tied to the > estimate of the bdi write speed. > > We _do_ have that avg_write_bandwidth thing in the bdi_writeback > structure, it sounds like a potentially good idea to try to use that > to estimate when to do writebehind. > > No? I really like the feature, and agree it should be tied to the bdi write speed. How about just making the tunable acceptable time of write behind dirty? Eg if write_behind_msec is 1000, allow 1s of pending dirty before starting writbeack. -- Jens Axboe
