Hi Ming & Jens, On Fri, 2018-07-13 at 12:54 -0600, Jens Axboe wrote: > On 7/12/18 5:29 PM, Ming Lei wrote: > > > > Maybe you can try the following patch from Christoph to see if it > > makes a > > difference: > > > > https://marc.info/?l=linux-kernel&m=153013977816825&w=2 > > That's not a bad idea. Are you saying that the previous "nasty hack" in bio_iov_iter_get_pages() was broken, and the new one is not? I've scratched my head over that (old) code lately, but I couldn't spot an actual error in it. Unfortunately we can only do one test at a time. We're currently trying to find out more about the IO sizes at which the problem occurs. As you noted, currently we know no more than that it happens somewhere between 16k and 1M. Martin -- Dr. Martin Wilck <mwilck@xxxxxxxx>, Tel. +49 (0)911 74053 2107 SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton HRB 21284 (AG Nürnberg)
