Re: How can I boost block I/O performance

[Avi Kivity <avi@argo.co.il>]

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.