The pernicious USB-stick stall problem

Posted Nov 7, 2013 14:48 UTC (Thu) by jzbiciak (guest, #5246)
In reply to: The pernicious USB-stick stall problem by nix
Parent article: The pernicious USB-stick stall problem

a device which goes from above-SSD speeds to USB-key speeds on the fly

I guess it depends on whether there are devices that have their own in-built caching and can absorb quite a few writes until they slow down dramatically. They could exhibit rather bimodal behavior based on the size of the incoming writes. Also, where does NFS fit in the picture? There, performance may fluctuate quite a bit as well, although I don't know if it's affected by this particular set of knobs. (Seems like it ought to be.) With NFS, you have the combined effects of the buffering on the NFS server as well as all the other people on the network vying for the same bandwidth.

My gut feel tells me any simple-minded rate estimator should also have a fairly quick adaptation rate so it tracks any workload-dependent behavior and other variations in media performance. ie. it should probably represent recent history (the last several seconds), more than long-term history.