> So this sounds like the backup is just thrashing your cache. I think it's more than that. Starting an rxvt shouldn't take 8 seconds, even with a cold cache. Actually, it does take a while, so you do have a point. I just did echo 3 > /proc/sys/vm/drop_caches and then started rxvt. That takes about 3 seconds (which seems long, but I don't know wherein that slowness lies), of which maybe 0.25 seconds is loading and running 'date': $ time rxvt -e date real 0m2.782s user 0m0.148s sys 0m0.032s The 8-second delay during the rsync must have at least two causes: (1) the cache is wiped out, and (2) the rxvt binary cannot be paged in quickly because the disk is doing lots of other I/O. Can the system someknow that paging in the rxvt binary and shared libraries is interactive I/O, because it was started by an interactive process, and therefore should take priority over the rsync? > Does rsync have the option to do an fadvise DONTNEED? I couldn't find one. It would be good to have a solution that is independent of the backup app. (The 'locate' cron job does a similar thrashing of the interactive response.) -Sanjoy `Until lions have their historians, tales of the hunt shall always glorify the hunters.' --African Proverb -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>