Nearly every piece of hardware in my laptop has worked fine, more or less, with Linux since I bought it early in 2010. There is only one minor buglet that I am aware of and it has been a minor nuisance the entire time: ACPI is unable to read the discharge rate of the battery.

This hasn't really been that big of an issue for me. The battery only lasts about two and a half hours anyway, and there is no trouble reading the current charge left in the battery. I was hoping I'd eventually luck out and a kernel upgrade would magically start seeing the discharge rate. I'm up to 3.0-rc3 and still no luck there.

I didn't have any reason to attempt to fix this problem until yesterday. I installed a copy of the latest and greatest development version of Powertop, version 1.98. The new version looks very promising. I was interested in trying the new calibration feature. It looks like it does things like cycle your LCD brightness, perform disk i/o, and stress the CPU a bit while monitor power usage. This doesn't seem to work so well if Powertop is unable to read the battery discharge rate.

My DV8T has a quad core i7 processor and the BIOS version was F.11. I bought two more DV8T laptops last summer, one for each of my parents. Theirs have Core 2 Duo processors. Luckily for me, I have a VPN between here and my parents' house. I was able to ssh into my mother's laptop and take a look around. She has BIOS version F.24 and ACPI has no trouble reading the discharge rate.

Updating the BIOS

I rarely update the BIOS on my machines. As far as I'm concerned, if it ain't broke don't fix it. I decided that, in this case, it seemed to be working on another very similar machine (with the same BIOS) that it was worth giving it a shot.

Here's the rub. HP's flash utility only runs on Windows. I don't have Windows installed anywhere here at home. I probably have an old Windows XP CD squirreled away somewhere, but I have no idea where it is. I'm disappointed that they don't have a DOS utility like most of their competition does. It isn't a deal breaker. I'd still buy another laptop like this, I don't often want to flash the BIOS on any of my laptops.

I tried a BartPE boot disk. It blue screened. I ended up downloading the Windows 7 Enterprise 30 day trial from MicroSoft and I installed it on an old spare laptop drive. This part of the journey is pretty uninteresting. Windows 7 installed just fine and the BIOS flashed with just a few clicks.

Total waste of time

I'm up to BIOS version F.25. Here is the result:

wonko@zaphod:~$ cat /proc/acpi/battery/BAT0/state
present:                 yes
capacity state:          ok
charging state:          discharging
present rate:            unknown
remaining capacity:      4640 mAh
present voltage:         16434 mV
wonko@zaphod:~$ cat /sys/class/power_supply/BAT0/current_now 
cat: /sys/class/power_supply/BAT0/current_now: No such device
wonko@zaphod:~$

Note the present rate: unknown and the No such device. I'm guessing this ACPI problem only exists on the Core i7 DV8T laptops. At least I got to see how much the Windows install process has (and hasn't!) changed between Windows XP and Windows 7, for whatever that is worth...

My Intel 80 GB X25-M G2 in my laptop died recently. Everything was running smoothly when I shut down but when I powered back up the BIOS couldn't see the drive any longer. Fortunately, I keep pretty good backups and I was up and running on a spare platter drive relatively quickly.

The RMA process was pretty disappointing. Phoning Intel was the only option.

I called in the afternoon on Monday, February 1, since they are only available during business hours. My time on hold was pretty short, probably about five minutes and it took less than 10 minutes to get the RMA rolling. I was told I'd receive an email shortly with RMA instructions.

I didn't receive an email. At that point it was after business hours so I used their web based form to submit a question. I included my RMA and case numbers, and I never heard back from them.

At this point there is a delay that is completely my fault. I didn't get a chance to call back until a week later on Monday, February 8. It turned out they got my email address wrong. I pronounced my email address and I spelled it to them letter for letter. They didn't only have it wrong, they were short on characters...

I was happy with the turn around time on the package. I had the drive at the post office on Tuesday, February 9 and the new drive arrived at my door on Tuesday, February 16.

The night of my second call to Intel I realized there was a pretty good chance they also didn't get my address correct. They do not include your shipping address in the RMA email. This time I sent an email to the address listed in the RMA email which is rma@mailbox.intel.com. I never heard anything back.

My Overall Opinion

I was happy with the service once I was able to get to the point where I was able to ship the drive out. I'm generally unhappy with their telephone support, and I am extremely disappointed with their email communications.

I Sure Did Miss the SSD

Certain tasks were noticeably slower. Most of the time the performance difference isn't something you can feel but some disk intensive tasks are significantly faster with the SSD. Things like booting, installing and updating a large number of packages with apt, and importing photos into F-Spot are at least twice as fast with the X25.

The thing I noticed most was the heat. When I first moved from the old hot platter drive to the X25 I didn't think the difference was so dramatic. Running on the SSD for months sure made the platter drive feel scary hot. The SSD is warm underneath the laptop where there is only piece of plastic covering and physically touching the drive.

The platter drive even made the top of the laptop very warm to the touch. The difference in temperature is huge.

• Update: The replacement drive died in the middle or April 2010 (about 3 months later). It died in a different make/model laptop (HP dv8t), but under similar circumstances. The drive was fine when the laptop was cleanly shut down, the BIOS could no longer see the drive on next boot. The replacement-for-the-replacement has been running fine since then, it is now September 2010.

The wiper.sh script that ships with hdparm 9.27 does not work well with the Intel X25 drives. The call to hdparm will fail if it is passed in more than 512 ranges of sectors. I made a quick and dirty modification to the wiper.sh script so that it makes multiple calls to hdparm with 500 ranges each. I've only been running it for a few days, but it seems to be working just fine so far.

I also added a --yes command line switch so that I could more easily call it from cron.

wonko@zaphod:~$ sudo ./wiper-dangerous.sh --commit --yes /

wiper-dangerous.sh: Linux SATA SSD TRIM utility, version 2.5-dangerous, by Mark Lord.
Preparing for online TRIM of free space on /dev/sda2 (ext4 mounted read-write at /).
Creating temporary file (3091782 KB).. 
Syncing disks.. 
Beginning TRIM operations..

/dev/sda:
trimming 6183568 sectors from 159 ranges
succeeded
Removing temporary file..
Syncing disks.. 
Done.

The script also now has a dependency on Perl. Feel free to download a copy of my wiper-dangerous.sh, but I make no promise that it won't eat your data!

I updated the firmware on my X25-M today. It was a completely pain free procedure. Just burn a CD, boot from the CD, say yes a few times, and reboot.

I added a new set of Bonnie++ benchmarks to my first set of Intel X25-M benchmarks.

Unfortunately, the new benchmarks aren't a good comparison. I have been using the drive for a month now and I probably have 100 GB worth of rewrites on the drive.

There were two obvious improvements. Sequential input is up 30%, and CPU usage during random seeks is down 12%.

I can't wait to try running another benchmark after I get some TRIM support in my kernel.

There seem to be plenty of X25 performance benchmarks all over the Internet. Performance may have been one of the major reasons I upgraded my laptop to an X25, it most certainly wasn't the only one.

Most of the power consumption benchmarks I have found don't seem to align very well with my usual on-battery workload. I am armed with a fresh battery and a new 80 GB X25-M, so I have to do some testing!

The Test Hardware

The laptop is a Dell Inspiron 6400 with a 1.66 ghz Core 2 Duo, ATI Radeon x1400 (using open source Radeon driver), Intel 3945 wireless card, and 4 GB RAM (only 3.16 GB usable). The laptop is running 64 bit Ubuntu 9.04.

My Testing Workload

I made sure most of my usual applications were up and running before I unplugged the power cord. That would include emacs, Firefox, Thunderbird, Pidgin, and Powertop. Bluetooth is turned off, wifi is connected to an 802.11a network, and the LCD brightness is set to 48%.

I spent run time of the battery doing some or all of the following:

• Editing Perl code with emacs
• Reading email
• Reading my RSS feeds with Google Reader
• Stumbling
• Trying to beat Hard creeps in the Desktop Tower Defense Sandbox mode
• Editing this blog entry
• Cooking a frozen pizza
• Brewing coffee in my Moka Express pot

The graphs!

Show:

For some reason my custom built 2.6.31 kernels are very power hungry. They are built based on the options in Ubuntu's 2.6.28 kernel config from my /boot directory, so they should not be configured too much differently than the Ubuntu 2.6.28 kernel. I don't have enough evidence to make me believe that 2.6.31 is any less energy efficient than 2.6.28.

It looks like I'm getting 10% more runtime with the SSD. I'm pretty happy with that. My 3 year old laptop has lots of outdated and power hungry components. The lowest wattage number I have seen out of powertop during these tests was in the 18.5 watt range. The long term averages powertop was giving me were in the 22-23 watt range.

I'm under the impression that modern laptops with LED backlights, better chipsets, and newer, faster processors can get into the 16 watt range with the LCD brightness turned all the way up (I was running mine at half). It wouldn't surprise me at all if a newer laptop would get a 15-20% improvement in runtime since their mechanical disk would be a larger percentage of total power.

Two Surprises Pointed Out By powertop

My laptop is already tweaked pretty heavily to save power, so I was surprised to see these two programs causing wake ups.

PostgreSQL was causing about 5% of my CPU wake ups. I really didn't want to have to shut down PostgreSQL so I was very happy to learn that there is a configuration option that can be tweaked in postgresql.conf. My postgresql.conf had the option commented out:

#bgwriter_delay = 200ms                        # 10-10000ms between rounds

I changed mine to 10000ms and I now I rarely see it show up in powertop.

The other surprise was gnome-power-manager. I thought I remembered it being fixed a few years ago. It used to wake up many times per second the entire time it was running. The current version that came with Ubuntu 9.04 seems to only be partially fixed. It seems that if it is running and the AC power state is changed it will revert to its old behavior of waking up 10-20 times per second.

Killing gnome-power-manager and restarting it will fix it until the next time the AC power state changes. I need to work on making that happen automatically.

Some Final Thoughts

The Intel X25-M is supposed to use 150mw when active and about half that when idle. Most mechanical drives don't even get down to 150mw when idle, and they require 1 to 2 watts or more when active.

A 10% increase in runtime on my 20 watt laptop fits those numbers pretty well.

I would imagine that power gap grows wider as the disk load increases. My usual on-battery workload is very light on the disks but it sure doesn't give them much chance to spin down.