In a self organised critical system such as the stock market, there will be days when it goes up, and days when it goes down. If this was not the case, then it would signal that something was wrong with the system, and I'd be getting scared.
Has anything fundamental changed at the companies that you have invested in to justify you changing your opinion of that company? Is CBA losing customers today in a way that it wasn't 3 days ago? Is BHP producing less copper or stated that it will miss any production hurdles?
If your investment logic was sound 3 days ago, it's still sound today. If you only sell shares when they drop 10% but are happy to buy when they go up a similar amount for fear of missing out, then you are guaranteed to blow through your cash in a hurry.
If you can pinpoint that the global rout is due to one specific factor that may disproportionately affect one of your portfolio holdings more than another, by all means re-evaluate, but absent that, just hold on for the ride. bulls are notorious for bucking...