Messages in this thread | | | From | Chet Nichols III <> | Subject | read_ahead_kb defaults to 0 on 2.6.9-55.0.6ELsmp | Date | Fri, 21 Sep 2007 15:01:41 -0400 |
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Hey there,
First time posting to the list, hopefully I'm following protocol.
We recently began rolling out updates to our RHEL4 hosts, which updated us to 2.6.9-55.0.6ELsmp.
However, upon reboot, we noticed I/O was being blocked a little more than usual. Looking into it, we noticed that the block device readahead was now being set to 0, instead of 8192 as it was with the previous 2.6.x kernel. (ie: the read_ahead_kb located in /sys/block/ cciss\!c0d1/queue/read_ahead_kb, at least for our systems)
In previous < 2.6 kernels where the readahead was managed by sysctl, we had a bunch of settings we'd manage ourselves. However, since it's an ioctl-managed setting now, I was under the impression the kernel would decide what it should be set at during boot.
Granted, we can always just echo in a value when the host is brought up, or run blockdev --setra, but we've never had to do this previously, so I feel like doing that now would just be a band-aid to the issue.
Is there something with this kernel I should be aware of, or has anyone noticed anything similar? Tried searching through some different threads looking for a similar issue, but to no avail.
Thanks in advance for all the help!
My best,
Chet
----- Chet Nichols III mail: chet.nichols@gmail.com aim: chet - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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