Date: Wed, 09 Sep 1998 00:30:05 +0300 From: Yoav Cohen-Sivan <ycs@netvision.net.il> To: freebsd-questions@FreeBSD.ORG Subject: Measuring interrupt latency for the serial port Message-ID: <35F5A1DD.386A6F0C@netvision.net.il>
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Is there a way to measure interrupt latency for the sio driver? I've been seeing random link lockups during almost every PPP session I initiate (both kernel and user). The lockups would clear after hanging up and redialling. I finally figured I'd lower my bps from 115200 to 57600, and voila! lockups have disappeared. I've spent the better part of the past 2 days banging on the link (and my phone bill) like there's no tomorrow. Since the lockups were usually during heavy link and system use, my thoughts are that the serial FIFO was overflowing, and the sio driver didn't have time to respond to the serial port interrupt. This probably caused some corrupted packets to be sent to my ISP (using Cisco 5200 equipment), causing it to ignore me for the duration of the session. Even though everything seems fine now, I'd still like to be sure that lowering the bps was the cure. Finally, is there a way to find out if the FIFO overflowed? Yoav To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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