When we deploy a class file using eclipse Force.com IDE, save command, does it make a deploy call? It is bizarre that it shows deployment logs for few req save commands and not others. I used ctrl+s to save a file and not 'save to server'. Yet its show deployment logs few times.
In the Force.com IDE there is a difference between saving the file locally and saving it to the SF server.
Saving it locally just saves the changes to your file system and doesn't compile it in Salesforce.
Saving it to the server uses a metadata api deploy call to compile the class in Salesforce.
The IDE doesn't save to the server by default - you have to explicitly tell it to save to server or adjust your settings to automatically save to server when you save the file locally. If you haven't set it to automatically save to the server then it's likely that you're seeing deploys only from times when the file was explicitly saved to the server.