
MacBook Air Mountain Lion Battery Life: 10.7.4 vs 10.8 vs 10.8.1 - tanousjm
http://www.macobserver.com/tmo/article/macbook_air_mountain_lion_battery_life_10.7.4_vs_10.8_vs_10.8.1/
======
Udo
I suspect something of huge impact happened in the graphics code. Maybe ML is
offloading way more tasks to the GPU (it probably has to in order to optimize
for Retina), maybe there are some hideous problems in the code - who knows.
It's all based on anecdotal observations of course.

My Mac Pro's fan noise, while unnoticeable under Lion, has gotten so loud it's
now uncomfortable to watch a movie with. It's only due to elevated
temperatures in the "expansion" area where the graphics cards are (the fans on
the cards are strangely quiet though). The underside of my 2011 MBP is about,
say, 5-10°C hotter on ML.

~~~
shinratdr
That's funny, I'm noticing cooldowns across the board when using ML on my Mac
Pro over Lion, although it's a Mac Pro 1,1. You might consider trying iStat
Menus and using it to narrow down the problem, it gives you all the temps of
the various locations in the Mac Pro. It will also let you adjust fan speed.

Make sure you reset the SMC too.

~~~
Udo
It's my fault for not being more precise. It's an early 2008 (3,1) Mac Pro
with 3 Nvidia GT 120 cards. iStat _is_ the tool I used to determine _which_
areas/fans are running so high: it's the "Expansion Slots". Resetting the SMC
was the first thing I tried, it did nothing (which is not unexpected since fan
speed starts out normal after startup, then increasing to an uncomfortable
1600 RPM after about 20 minutes).

At this point I'm considering locating the temp sensor to stick a piece of gum
on it or maybe disable it outright.

I'm a little ashamed to say that the other alternative is a downgrade to SL,
which for the purposes of making peace with a once beloved OS I shall refer to
as "The Good Old Times" from now on.

~~~
shinratdr
I would bet you anything it's those stupid GT120s. There is a reason you can't
buy them from Apple anymore. They basically never made a decent Nvidia card.
Or, wait for an ML graphics update. $20 says it will solve your problem.

The 4870/5870/6870 is a good choice if you're looking for something more
compatible. The drivers for that series are steadily getting better and you
can use the PC versions right out of the box with no modifications.

However if you have 3 GT120s for the reason I suspect, you need to power six
displays or three dual DVI displays, then you're stuck.

~~~
Udo
Like I said it was fine on Lion and before. Fork over those 20 bucks ;)

I don't think there will be a graphics update for ML by the way. The MP (and
whatever cards it uses) is an obsolete platform.

Thanks for suggesting alternative graphics, but I already upgraded from the
previous gen ATI cards a few months ago and I'm not likely to buy more parts
for this machine again. At this point I'm waiting what Apple does with the Pro
and maybe buy a new one (or just leave Apple if they screw this product up too
badly).

~~~
shinratdr
> Like I said it was fine on Lion and before. Fork over those 20 bucks ;)

Sorry I didn't mean there is a hardware problem with the cards, just that the
hastily written ML GT120 drivers are most likely the culprit.

> I don't think there will be a graphics update for ML by the way.

Graphics updates are an expected part of an OS X release cycle at this point.
We had one for SL, and Lion, and I would expect one for ML. Touchups across
the board. What you're ignoring is that you already got a graphics update. By
upgrading to ML, you're now on the 64-bit kernel and therefore are using the
64-bit kexts.

> The MP (and whatever cards it uses) is an obsolete platform.

Apple reaffirmed their commitment to the Pro line, so I wouldn't assume that
so quickly. Also, behind the scenes evidence highly suggests that isn't the
case. If Apple is planning to ditch the Mac Pro, they sure are steadily adding
PC graphics card support for no explicable reason to OS X then.

Between 10.6.8 and 10.8.1 we've had support added for generic ATI cards and
Nvidia cards of all stripes. Before 10.6.8, you simply couldn't boot a Mac Pro
without an official card or card reflashed with EFI firmware.

Now, I haven't had an Apple official or reflashed card in my Mac Pro in a year
and I use it every day, including right now. None of this has yet resulted in
a product Apple actually sells. That bodes quite well for the future of the
Pro line.

------
neverm0re
I'd really like to see Snow Leopard added to this, because absolutely all
personal testing I've done has shown that we've been in a steady descent from
that point if you care about things like battery life and performance. I
simply don't have enough time to objectively measure this, unfortunately, but
if you take the aggregate of various benchmarks and reviews, that seems to be
the consensus anyway.

~~~
toadkick
I posted a very similar reply to a post a couple of days ago linking to the
same article (uh..see EDIT below, this is slightly different article),
submitted by the same person, who also happens to be the the author of the
story (<http://news.ycombinator.com/item?id=4425673>). It appears that post
was either flagged or downvoted into oblivion, because it disappeared shortly
thereafter (and after seeing this hit again 2 days later, I'm thinking it was
pretty justifiable...)

EDIT: okay, so I missed a small detail, the other was about the MBP, this one
is about the MBA. My bad..I guess.

Anyway, my experience has been largely the same as yours...I lost a
significant amount of battery life when I upgraded to Lion, and apparently it
seems like the problem is only getting worse.

The author replied in the other post that he would add Snow Leopard to the
test, which should be interesting...I'm expecting that the difference between
Snow Leopard and Mountain Lion will be _huge_.

~~~
tanousjm
Hi toadkick,

Yep, I'm currently sitting here running 10.6.8 battery life tests as we speak.
I'm going to make it as comprehensive as I can and run multiple tests on each
build of OS X from 10.6.8 to 10.8.2 (prerelease). It will take a while; should
be ready by the middle of this coming week.

~~~
gurkendoktor
...and that is after 10.6 supposedly lowered battery life too:

[http://www.anandtech.com/show/2870/done-for-2009-the-
holiday...](http://www.anandtech.com/show/2870/done-for-2009-the-holiday-
macbook-pro-roundup/7)

I tried 10.5-10.8 on the same MacBook Pro and anecdotally, it really is a
downward trend. Looking forward to your benchmarks.

~~~
neverm0re
Though 10.6 did improve overall benchmark performance from 10.5 which was
arguably the first regression in OS X, which from its rough inception managed
to get better by the point release. It's actually rather alarming that 10.8 is
a continuation in decline rather than making up from 10.7's failings.

I switched from using OpenBSD on all my laptops at 10.3 and now I find it very
difficult to continue justifying OS X with all of these performance
regressions and how increasingly annoying it is to treat the OS as a solid
desktop *nix, which is all I ever wanted. As much as I admire DragonflyBSD,
I'm likely going to Linux next.

(What I really miss was how snappy and responsive IRIX was...)

~~~
gurkendoktor
The most frustrating thing is that both "the internet" (the blogosphere or
whatever you'd call it) and sales numbers are absolutely in favor of Apple's
strategy. Sometimes I need to open up the Mac App Store to look at all the
grumpy one-star reviews for 10.8, just to know that humanity hasn't completely
lost its mind.

------
dmak
Should have done a SMC and PRAM reset before performing the tests.

~~~
forgotusername
And of course, not forgetting repair permissions, a quick shake of the blessed
ju-ju stick in an easterly direction, and the feeding of at least 2 manna
cookies to the Jobs voodoo doll.

More seriously, has SMC/PRAM reset ever fixed anything for anyone?

~~~
stordoff
kernel_task on my rMBP was hitting 100% CPU at seeming random times (about
once a day), and it would stay there until I rebooted. SMC/PRAM reset seems to
have stopped it happening.

------
Casseres
The OP (tanousjm) posted the same thing 2 days ago:

<http://news.ycombinator.com/item?id=4425673>

I'm relatively new to HN, but I believe the first comment on tanousjm's
original submission is noteworthy (especially since tanousjm posted the same
thing twice in as many days).

~~~
tanousjm
These are different articles, Casseres. First one was MacBook Pro battery
tests, this is a follow-up with MacBook Air tests.

------
Someone
The way I understand Gatekeeper, it must checksum an app on disk whenever it
starts up (correct me if I am wrong)

If that is true, this test may not be representative of typical use; it
contains way too many application launches.

I would like to see the effect of Gatekeeper settings on battery life.

~~~
astrange
Gatekeeper only runs the first time something is downloaded and has nothing to
do with it.

Codesigning does verify programs each time they are run and this has not
changed in many OSes.

~~~
Someone
I checked this, but only got more confused. I made a copy of TextEdit, did all
kinds of things with it (append some text to the executable, edited Info.plist
and version.plist, threw away a zillion localizations, threw away the
_CodeSignature directory), and never got Mountain Lion to complain. The
mangled either launched or, in one case (I tried renaming the executable and
adjusting the .plists to match), did not launch at all.

The only way I could get a code signing warning is by adding the
com.apple.quarantine extended attribute (using xattr)

So, it looks like Mountain Lion only does a signing test for just downloaded
apps, and then, I guess, only for downloads by applications that cooperate and
set that flag.

I do think Apple has considered/is considering/would like to add more testing,
though. Otherwise, I cannot explain the -P flag for codesign:

    
    
      -P, --pagesize pagesize
          Indicates the granularity of code signing. Pagesize must be a power of two.
          Chunks of pagesize bytes are separately signed and can thus be independently
          verified as needed.  As a special case, a pagesize of zero indicates that the
          entire code should be signed and verified as a single, possibly gigantic
          page. This option only applies to the main executable and has no effect on
          the sealing of associated data, including resources.

~~~
jasomill
This is all by design, and you're surely right about Apple doing more with
code signing in the future. In the past, signatures have mostly only been
checked in very specific circumstances (e.g., designated requirements for two
programs to be considered equivalent by Keychain and the firewall), though the
architecture is fairly general, so third parties have been free to cook up
their own applications. Still are, though there is no alternative to Developer
ID for the Gatekeeper checks, which seems sensible from a KISS perspective, so
long as reasonable workarounds exist for developers unwilling or unable to
sign with a Developer ID (certainly true today).

------
tanousjm
10.8.1 improved things a little bit, but running time is still short of where
it was in Lion.

We only have one Mac in our test suite that can support it, but we're going to
try to test the 2011 MBP with Snow Leopard and compare that to the results on
the same machine for Lion and Mountain Lion.

~~~
mikeash
How many tests do you run with each configuration? I'm wondering what sort of
variation these test have, but it doesn't appear to be discussed.

~~~
tanousjm
You're right; I'm sorry I missed discussing that. Our testing methodology is
to run each test at least 2 times and if the second test is within 5 percent
of the first, to average the two results. If there's a greater than 5 percent
difference, we run multiple tests until we can determine which result was
abnormal and why.

It's not THE most scientific methodology, but it's a decent balance between
time and accuracy. In the case of our most recent round of tests, none of the
second results were more than 4 percent off the first test.

~~~
mikeash
I'm really pleased to hear that. Given the lack of discussion I had assumed
the worst, but I'm glad to be wrong, and sorry to presume otherwise. Thanks a
lot for following up.

------
kine
I hope this makes some kind of a difference on my 2010 Air. 10.8 really
destroyed the battery on this thing.

~~~
dave1619
10.8.1 seems to have improved my battery life on my MBA from 10.8. 10.8 really
killed the battery life. But 10.8.1 I'm noticing improvement.

