Re: How can I boost block I/O performance

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

Dave Pitts wrote:
> Hello all:
>
> I've been trying some hacks to boost disk I/O performance mostly by 
> changing values
> in the /proc/sys/vm filesystem.  A vmstat display shows bursty block 
> out counts with
> fairly consistent interrupt counts:
>
> 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?

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