Messages in this thread | | | Subject | Re: [PATCH] iomap: Fix the write_count in iomap_add_to_ioend(). | From | Ritesh Harjani <> | Date | Fri, 21 Aug 2020 14:39:33 +0530 |
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On 8/21/20 11:30 AM, Christoph Hellwig wrote: > On Fri, Aug 21, 2020 at 10:15:33AM +0530, Ritesh Harjani wrote: >> Please correct me here, but as I see, bio has only these two limits >> which it checks for adding page to bio. It doesn't check for limits >> of /sys/block/<dev>/queue/* no? I guess then it could be checked >> by block layer below b4 submitting the bio? > > The bio does not, but the blk-mq code will split the bios when mapping > it to requests, take a look at blk_mq_submit_bio and __blk_queue_split.
Thanks :)
> > But while the default limits are quite low, they can be increased > siginificantly, which tends to help with performance and is often > also done by scripts shipped by the distributions. > >> This issue was first observed while running a fio run on a system with >> huge memory. But then here is an easy way we figured out to trigger the >> issue almost everytime with loop device on my VM setup. I have provided >> all the details on this below. > > Can you wire this up for xfstests? >
Sure, will do that. I do see generic/460 does play with such vm dirty_ratio params which this test would also require to manipulate to trigger this issue.
Thanks for the suggestion! -ritesh
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