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.

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