Am 30.05.2012 20:47, schrieb Stefan Majer:
From my perspective marks hints regarding blktrace end up in the same
summary as the iostat ouput gives.
You see stalls, not induced by disk by any means, no other obvious hints
where the lag might come from.
So if you want to know why kernels > 3.2 are slow for your workload i
would drill down this with git bisect.
OK here are some tests regarding the kernel version - all made with XFS.
Starting with 3.2.0-rc1 it drops from 164MB/s (bonding) to 119MB/s but
it never goes down to 0MB/s. 3.2.18 shows the same as 3.2-rc1.
Then with 3.3-rc1 i'm seeing even faster speed (178MB/s) than with 3.0.X
- so everything is fine again. So it seems 3.2.X had another bug which
reduced the speed which was fixed in 3.3.
Beginning with 3.3-rc4 it get's bad with drops to 0MB/s. So it should be
a commit between 3.3-rc3 and 3.3-rc4. Sadly this are 370 commits. No
idea where to start.
Stefan
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