> > I think the only way to switch schedulers is to reboot. You invoke > > the noop scheduler via a command line arg to the kernel at boot time. > > This can be done at any time, no reboot required: > > for f in /sys/block/*/queue/scheduler; do > echo noop > $f > echo $f "$(cat $f)" > done OK, I did this. Two questions: 1. The system responded in each case with this: "/sys/block/<block device>/queue/scheduler [noop] anticipatory deadline cfq". Is this as expected? 2. To switch back to the default scheduler, which I take it is CFQ, do I simply issue the command above, replacing the string "noop" with "cfq"? > Just FYI, I don't think ionice and friends will work when using noop. > > Leslie: I still think finding out what the kernel is doing during the > stall would be a HUGE hint to the problem. Did you look into oprofile or > ftrace? I couldn't find a Debian source for ftrace, but I did download oprofile. I am going to require some guidance, however. I understand in general terms what oprofile does, and vaguely what is involved with setup and configuration, but it's quite a powerful and flexible tool, and I have little or no idea of where to head with specifics. If someone would care to send a little guidance on what parameters I need to employ for setup and configuration, and what processes I need to profile, I would be most grateful. Not knowing what to expect for an output, I may also require some help with analysis. If anyone wishes to help, but would prefer to take it offline, please feel free to e-mail me directly. Otherwise, please respond here. -- 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
