Load testing of a desktop application having client server architecture

I need to do load testing of a desktop application.

Requirement is that:

• Application is installed at various clients.
• All client have a common DB server.
• Data submitted by one client is visible to other clients also just after submission of data.

I need to check that after submission in how much time the data get populate to different concurrent clients.

Please suggest me an open source tool or way to measure this.

Let me know in case of any more information is required.

Thanks in Advance!!