Performance not what it should be; what can I do?

[crakie]

I installed Ubuntu Jaunty on my brand new Vertex 30 Gb (FW v1.3), which now takes up about 10 Gb. Some tasks, particularly the boot, are noticeably faster, but on the whole it's not what I expected. For example, I thought I would never have to see 5 Mb/s write speeds again, but this is what gnome tells me at many copy operations.

Here are some benchmarks for reading on the Vertex (/dev/sdd) I found on this forum:

1) hdparm -t /dev/sdd: 123 Mb/s (with --direct 130 Mb/s)
2) dd if=/dev/sdd of=/dev/null bs=4k skip=0 count=51200: 129 Mb/s
3) Bash testscript provided by b2bde4: 140 Mb/s (8192k blocks)

These were all performed at the terminal, with X not running. The good news is, they are pretty much the same when the system is in full use. Still, I encountered much better results here and elsewhere.

So, what can I do to improve this (let's start with the reading speed)? I used the partition alignment howto by TortureTest, used the strip-width option when creating the ext4 partition, use the noatime option and changed the scheduler to deadline. Naturally, the swap file is not on the SSD (but also not on a ramdisc).

[b2bde4]

It's almost like those numbers where capped by sata generation I. Strange.

Did you try to connect your Vertex on the first sata port?
Did you try to disconnect the other disks?
Did you try to switch between AHCI and IDE mode?
Did you try some simple benchmark from your windows installation.

[crakie]

It's almost like those numbers where capped by sata generation I. Strange.

I always had the impression the controller (ICH8R) on the Abit was not performing optimally. A Raid0 of Spinpoints never got close to the usual benchmarks either.


Did you try to connect your Vertex on the first sata port?
Did you try to disconnect the other disks?
Did you try to switch between AHCI and IDE mode?
Did you try some simple benchmark from your windows installation.

Since most of these suggestions would probably loosing the ability to boot from that SSD and I just spent 2 hours setting up Mythtv (yes, silly me), I decided to try something less radical first: flashing the bios (which I could have sworn was the most recent already) and the drive (v1.3 -> v1.3 for sure). The results:

hdparm: 172 Mb/s
dd: 181 Mb/s
script: 22 Mb/s (2 Kb), 207 Mb/s (8192 Kb)

Pretty good, huh?

I also tried copying about 1 Gb from a harddisc to my SDD. Gnome does not show the speed in the first few seconds (100 Mb or so), first value shown was 10 Mb/s shooting up to 20 Mb/s. What's a good tool to benchmark writing?

[ColdCanuck]

I also tried copying about 1 Gb from a harddisc to my SDD. Gnome does not show the speed in the first few seconds (100 Mb or so), first value shown was 10 Mb/s shooting up to 20 Mb/s. What's a good tool to benchmark writing?


For a quick and dirty try:


dd if=/dev/zero of=FILENAME bs=4k (16k, 256k or 1M...) count=whatever-it-takes conv=fsync

for most accurate results, make sure you set "whatever-it-takes" to a value which causes the file to be at least twice your memory.

However much smaller files will be a good approximation as long as you use the conv=fsync.


This will test a write via the OS and is representative of what a cp from a shell prompt will give you. This is NOT the raw writing rate but the all up cooked one.