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SubjectRe: How can I boost block I/O performance
Dave Pitts wrote:
> Avi Kivity wrote:
>
>> Dave Pitts wrote:
>>>
>>> procs -----------memory---------- ---swap-- -----io---- --system--
>>> ----cpu----
>>> r b swpd free buff cache si so bi bo in cs us
>>> sy id wa
>>> 4 0 720 80252 1820 7077456 0 0 9 852 5 11
>>> 1 14 84 0
>>
>> [...]
>>
>>> 5 0 720 90364 1860 7067080 0 0 40 66956 17995 95384
>>> 0 17 82 0
>>>
>>> This test is running several NFS clients to a RAID disk storage
>>> array. I also see the
>>> same behavior when running SFTP transfers. What I'd like is a more
>>> even block
>>> out behavior (even at the expense of other apps as this is a file
>>> server not an app
>>> server). The values that I've been hacking are the
>>> dirty_writeback_centisecs,
>>> dirty_background_ratio, etc. Am I barking up the wrong tree?
>>
>> No iowait time, plenty of idle time: looks like you are network
>> bound. What time of network are you running?
>>
> Well, it's an 8 cpu system. Does the idle time reflect the idle time
> of all cpu's?

It's an average across all cpus. But the numbers are low even for a
single cpu system.

> The network is a Gigabit Ethernet.
>

I'd make sure the nics know that by running ethtool (on the clients as
well as on the server).



--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

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