Messages in this thread |  | | From | Aaron Carroll <> | Date | Sat, 22 Mar 2008 23:09:27 +1100 | Subject | Re: deadline unfairness |
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Bernd Schubert wrote: > Hello, > > some it seems the deadline scheduler is rather unfair. Below is an example > of md-raid6 initialization of md3, md4 and md5. All three md-devices > do share the same blockdevices (we have patched md to allow > parallel rebuild of shared block devices, since for us the cpu is the > bottleneck and not the block device). > > All rebuilds started basically at the same time, as you can see, md3 is already > done and now md4 rebuilds substantially faster than md5. > [..] > This is basically with a 2.6.22 kernel + lustre + md-backports, but nothing > done to the scheduler.
Hi Bernd,
There is a deadline bug in pre-2.6.24 kernels where lower-sector requests can starve higher-sector requests; you might be hitting this bug. It was fixed by commit: 6f5d8aa6382eef2b26032c88656270bdae7f0c42
-- Aaron
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