Re: [BENCHMARK] max bomb segment tuning with read latency 2 patch in contest

GrandMasterLee
2002-12-07T06:12:42Z

On Fri, 2002-12-06 at 23:55, Andrew Morton wrote:
[...]
> If the SMP machine is using scsi then that tends to make the elevator
> changes less effective. Because the disk sort-of has its own internal
> elevator which in my testing on a Fujitsu disk has the same ill-advised
> design as the kernel's elevator: it treats reads and writes in a similar
> manner.
>
> Setting the tag depth to zero helps heaps.
>
> But as you're interested in `desktop responsiveness' you should be
> mostly testing against IDE disks. Their behavour tends to be quite
> different.

One interesting thing about my current setup, with all scsi or FC disks,
is that bomb never displays > 0.
Example:

elvtune /dev/sdn yields:

/dev/sdn elevator ID 17
read_latency: 8192
write_latency: 16384
max_bomb_segments: 0

elvtune -b 6 /dev/sdn yields:

/dev/sdn elevator ID 17
read_latency: 8192
write_latency: 16384
max_bomb_segments: 0

Is it because I just do volume management at the hardware level and use
whole disks? Or is that something else?