A320 flight crew reported a fumes event of varied intensities from departure gate to destination arrival. The reported 'dirty socks' odor was nearly imperceptible during cruise and became more intense during destination descent. Maintenance requested at gate arrival.

Narrative

Upon selecting the APU bleed near the conclusion of boarding; a noticeable dirty sock odor was present in the cockpit. The smell remained; although slightly less intense through pushback until engine start when the odor's intensity returned. The smell remained through the takeoff and climbout; varying in intensity with the power settings of the engines; at times not just as a perceptible odor; but also felt in our eyes and sinuses.During the climb we tried to isolate which ducting was the source of the odor. After deselecting pack 1 the smell was greatly reduced and eventually dissipated to near undetectable levels. We queried the flight attendants in the forward and aft cabins and they reported no odor whatsoever at any stage to that point in the flight. Due to the nearly imperceptible level of odor at cruise and no odor in the cabin; we checked the QRH for guidance and opted to continue the flight on pack 2.On descent the intensity of the odor returned when the high pressure bleed opened; and was especially noticeable on final approach. We landed and had to wait about ten minutes for a gate so we decided to try to isolate the ducts to see where the renewed intensity was coming from. While pack 2 had high odor with the high pressure bleed valve open; again perceptible in our sinuses and eyes; when switching to pack 1 the odor was so intense that we immediately discontinued its use and taxied in on pack 2. Again; there were no complaints from inflight of any odor whatsoever.[At] the gate we contacted Maintenance Control; filled out the odor form and wrote up the issue in the logbook. When Air Carrier tech ops showed up at the airplane; we briefed the tech and turned the airplane over to him for troubleshooting. After the flight; the sensation in our eyes remained; but could have been fatigue as we didn't notice any other physical symptoms of the odor event.