[lustre-discuss] Large file read performance degradation from multiple OST's

[Vicker, Darby (JSC-EG311)]

Using the git bisect we were able to isolate the problem to this commit:

commit d8467ab8a2ca15fbbd5be3429c9cf9ceb0fa78b8
    LU-7990 clio: revise readahead to support 16MB IO

In our testing, we can read from a large file (stripe count=4) at near line rate (10 GbE – so 1200 MB/s) using a client compiled with the commit before this one.  With this patch, the read rate drops to ~200 MB/s.
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