Messages in this thread |  | | | Date | Wed, 9 Feb 2011 18:45:25 -0800 | | Subject | Re: [PATCH] Avoid preferential treatment of groups that aren't backlogged | | From | Chad Talbott <> |
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On Wed, Feb 9, 2011 at 6:09 PM, Vivek Goyal <vgoyal@redhat.com> wrote: > In upstream code once a group gets backlogged we put it at the end > and not at the beginning of the tree. (I am wondering are you looking > at the google internal code :-)) > > So I don't think that issue of a low weight group getting more disk > time than its fair share is present in upstream kernels.
You've caught me re-using a commit description. :)
Here's an example of the kind of tests that fail without this patch (run via the test that Justin and Akshay have posted):
15:35:35 INFO ----- Running experiment 14: 950 rdrand, 50 rdrand.delay10 15:35:55 INFO Experiment completed in 20.4 seconds 15:35:55 INFO experiment 14 achieved DTFs: 886, 113 15:35:55 INFO experiment 14 FAILED: max observed error is 64, allowed is 50 15:35:55 INFO ----- Running experiment 15: 950 rdrand, 50 rdrand.delay50 15:36:16 INFO Experiment completed in 20.5 seconds 15:36:16 INFO experiment 15 achieved DTFs: 891, 108 15:36:16 INFO experiment 15 FAILED: max observed error is 59, allowed is 50 Since this is Jens' unmodified tree, I've had to change BLKIO_WEIGHT_MIN to 10 to allow this test to proceed. We typically run many jobs with small weights, and achieve the requested isolation: see below results with this patch:
14:59:17 INFO ----- Running experiment 14: 950 rdrand, 50 rdrand.delay10 14:59:36 INFO Experiment completed in 19.0 seconds 14:59:36 INFO experiment 14 achieved DTFs: 947, 52 14:59:36 INFO experiment 14 PASSED: max observed error is 3, allowed is 50 14:59:36 INFO ----- Running experiment 15: 950 rdrand, 50 rdrand.delay50 14:59:55 INFO Experiment completed in 18.5 seconds 14:59:55 INFO experiment 15 achieved DTFs: 944, 55 14:59:55 INFO experiment 15 PASSED: max observed error is 6, allowed is 50 As you can see, it's with seeky workloads that come and go from the service tree where this patch is required.
Chad
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