On 4/24/2013 3:26 AM, Andrei Banu wrote: > Total DISK READ: 0.00 B/s | Total DISK WRITE: 0.00 B/s > TID PRIO USER DISK READ DISK WRITE SWAPIN IO> COMMAND > 541 be/3 root 0.00 B/s 0.00 B/s 0.00 % 96.96 % [jbd2/md2-8] This seems to be your problem. jbd2 (journal block device) is causing 97% iowait, yet without doing much physical IO. This is a component of EXT4. As this will fire intermittently it explains why you see such a wide throughput gap between tests at different points in time. This isn't a bug or Google would reveal that. Andrei, you need to identify which daemon or kernel feature is causing this. Do you happen to have realtime TRIM enabled? It is well known to bring IO to a crawl. If not realtime TRIM, I'd guess you turned a knob you should not have in some config file, causing a daemon to frequently issue a few gazillion atomic updates. -- Stan -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
