elevator=noop

I don't recommend adding this option to your kernel. It seems to cause the AAO to freeze without response for large periods of time when writing to the SSD drive. I took it out and rebooted, and ubuntu seems, to me, to be a lot more responsive now.

 

I can't say that I've experienced anything similar. What tasks are you performing when things "freeze"?

 

Yes, I've posted on this before.

It's most noticeable loading pages in Firefox, though disabling the caching of pages can help this. A few people, including me, have decided that elevator=deadline is a better choice. It just seems to work better, though there is nothing tangible, or scientific to prove it.

The elevator is meant to compensate for the access time on a mechanical hard disk while the heads travel to the correct spot on the disk surface. This isn't relevant to a SSD, so the noop option removes all of this optimisation and seems to be 'first in - first out'. The deadline option is like noop, but data is shifted to a dead line. I think this means that data that has been sitting around getting stale in the buffer is given more priority. This makes the system 'feel' more responsive - to me anyway.

 

I second all this. I used the parameter "deadline" like you suggested. Performance has significantly improved.

 

Although it I have no way of measuring this, I have had no freezes since I changed to deadline either - promising so far.

 

so how do you actually do the change?

 

Deadline also attempts to optimize the reads and writes for a normal spinning harddrive. What the deadline means is that an IO-request that hasn't been served witin a specified amount of time gets priority regardless where on the disk the blocks in question happen to be (iirc the default is 500ms for reads and 5000ms for writes). Possibly the optimization could be skipped by setting both read_expire and write_expire to 0 (and fifo_batch to 1) - been meaning to do some testing with it but not gotten around to it .

Anyway, the reason the system becomes more responsive is because deadline also gives higher priority to reads (deafault is two reads for each write). An application that's waiting for a read will usually freeze while write requests just return (and get cached by the kernel if the disk is busy).

 

You can either add elevator=deadline to the kernel options in /boot/grub/menu.lst (it's in all the guides IIRC, just substitute noop for deadline ), or do an echo "deadline" > /sys/block/sda/queue/scheduler - could be added to rc.local f.ex.

Btw, how come there's no way to add inline code-blocks in bbcode?

 

Thanks
I replaced noop with deadline and the system under linpus seems to be quicker

 

I concur that my Acerf Aspire One 110L running Ubuntu Ibex feels faster after changing "noop" to "deadline" in menu.lst. No hard data here, but it does feel faster. This is nice since the lagging sometimes really gets to me, despite all the optimisations i've done as per https://help.ubuntu.com/community/AspireOne110L.