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:

quoted

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

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SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton
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