[Lustre-discuss] How to track down a latency/timing problem

[Ashley Pittman]

On 12 Aug 2010, at 17:10, robert wrote:
> - Is there a way to check the amount of time that the different parts of
> a file operation take (like 1ms requesting metadata, 1ms receiving
> metadata, 123ms reading blocks from OST, ...)?

"strace ls" is interesting to watch if you haven't unaliased ls as below...

> - Does anyone have a hint on what could be the problem, where to search
> or what to do?

One very simple trick that I was un-aware of until it was mentioned at the lug is to unalias ls.  Most, if not all distributions alias ls to "ls --color" which causes ls to stat every single file in a directory to decipher it's type, running /bin/ls will improve the ls performance by several orders of magnitude.

Ashley,

-- 

Ashley Pittman, Bath, UK.

Padb - A parallel job inspection tool for cluster computing
http://padb.pittman.org.uk