2013 Haswell MBA - VM battery life

lamboman · Aug 23, 2013

Hi all,

I've already asked this in another thread, however I've struggled to find answers overall.

I will soon be purchasing an MBA 13", with 8GB of memory and the 256GB SSD. Usage will be typical productivity (word processing, browsing, etc), as well as the occasional Windows VM for programming, likely in Visual Studio (in Parallels, VirtualBox, or VMWare, whichever turns out to be the best solution overall).

Both the i7 and i5 have potential problems:

i7
For light-medium loads like a VM, it is possible that battery life could take a fairly significant hit over the i5.

i5
Many users have reported that the i5 model generally feels sluggish during normal usage (browsing, etc). I've certainly noticed this while playing with several models at the Apple Store. I have little doubt that this will become frustrating, and that the issue is likely down to the low clock speed during these tasks (the i5 will offer plenty of performance when pushed however). Opening new windows and applications, it is just slower than my previous 13" MBP (SB i5 2.3GHz, Crucial m4 128GB, and 8GB RAM).

Of course, under light loads (which will make up most of the usage), both machines are basically on par, the i7 possibly being a tad better. Under heavy loads, the i5 offers longer battery life, but under such loads I'll probably be performing a task that requires only a certain amount of work (eg. encoding a video) as opposed to an ongoing task (eg. running a VM). At that point, you'd probably plug the machine in anyway.

I don't want to get into a debate about whether the i7 offers more usable performance than the i5 for basic tasks. Those of us in the know can make our own decisions, and those who aren't have plenty of great resources (such as Anandtech's comparison) to come to their own conclusions (I will not state my view as this will undoubtedly instigate more pointless debates!). I will simply go for the model which has the fewest drawbacks - the likelihood is that if the i7 doesn't take a big hit while using a VM, I will go for that.

How have you guys found battery life with Parallels, VMWare, or VirtualBox with your i5 and i7 MBAs during similar types of work? Those of you who have or have had both, what differences have you found?

Those of you who have had or tried both the i5 and the i7, have you found that the i7 fixes the sluggishness that you have experienced with the i5 during general usage?

Hopefully this thread will be a good little resource for those Googling for answers!

Thanks all!

GGJstudios · Aug 23, 2013

There are many factors that impact your battery life much more than which processor you have. There isn't likely to be much difference between the i5 and i7 in terms of battery life, provided the workload is the same on both. See the BATTERY LIFE FROM A CHARGE section of the following link for details, including tips on how to maximize your battery life.



The link below should answer most, if not all, of your battery/charging questions. If you haven't already done so, I highly recommend you take the time to read it.

Apple Notebook Battery FAQ

lamboman · Aug 23, 2013

GGJstudios said:
There are many factors that impact your battery life much more than which processor you have. There isn't likely to be much difference between the i5 and i7 in terms of battery life, provided the workload is the same on both. See the BATTERY LIFE FROM A CHARGE section of the following link for details, including tips on how to maximize your battery life.

The link below should answer most, if not all, of your battery/charging questions. If you haven't already done so, I highly recommend you take the time to read it.
Apple Notebook Battery FAQ

As we've seen from Anandtech, as the load increases the battery life difference increases also. The i7 under medium and heavy workloads gets a fair bit less battery time than the i5. I'd say that running a VM is a fairly mixed load, therefore real life experiences are the best way to gather information. Thanks for the reply however

ZBoater · Aug 24, 2013

lamboman said:
As we've seen from Anandtech, as the load increases the battery life difference increases also. The i7 under medium and heavy workloads gets a fair bit less battery time than the i5. I'd say that running a VM is a fairly mixed load, therefore real life experiences are the best way to gather information. Thanks for the reply however

By "fair bit" they discovered 15-18% (52 minutes) under medium/heavy load. With as long as these batteries are lasting, 52 minutes is not a lot. I think you will get tired of sitting in one spot a lot sooner than the MBA runs out of battery.

http://www.anandtech.com/show/7113/2013-macbook-air-core-i5-4250u-vs-core-i7-4650u/4

lamboman · Aug 24, 2013

That's true, and my other point of view! My mind tells me that the extra hour could make a difference though!

It's a hugely frustrating decision! I think it's one of those things where the calculations of usage and the reality are very different - it could be that the i7 lasts more than enough in reality.

GGJstudios · Aug 24, 2013

lamboman said:
That's true, and my other point of view! My mind tells me that the extra hour could make a difference though!

It's a hugely frustrating decision! I think it's one of those things where the calculations of usage and the reality are very different - it could be that the i7 lasts more than enough in reality.

One question to ask yourself is how often do you have a need to run on battery to the limits of its capacity? For example, if you routinely run on battery 4-5 hours, and only rarely longer, then trying to get capability from 6 to 7 hours will rarely impact your real-world experience. Factors like workload and screen brightness have a much greater impact on battery life than processor selection.

lamboman · Aug 24, 2013

All true, and they have been part of my consideration! Majority of usage will be light for 7-8 hours, VMs will be occasional but will likely be for extended periods.

Any experiences? Thanks for the input thus far

ZBoater · Aug 24, 2013

lamboman said:
All true, and they have been part of my consideration! Majority of usage will be light for 7-8 hours, VMs will be occasional but will likely be for extended periods.

Any experiences? Thanks for the input thus far

My experience with VMs will unlikely help you make your decision. I use VMs mostly for Windows, and do use them a lot, but I never use my laptop for 7-8 hours on battery. I am just not that "mobile".

If I absolutely had to have the longest possible battery life, then I would choose the i5. However, I prefer to have the better performance. Its my preference because the extra 52 minutes (which in my case could actually be 30 minutes or 2 hours) was just not that important to me. As long as I could use the laptop for 3-4 hours on battery, I would be fine. But thats me.

lamboman · Aug 24, 2013

ZBoater said:
My experience with VMs will unlikely help you make your decision. I use VMs mostly for Windows, and do use them a lot, but I never use my laptop for 7-8 hours on battery. I am just not that "mobile".

If I absolutely had to have the longest possible battery life, then I would choose the i5. However, I prefer to have the better performance. Its my preference because the extra 52 minutes (which in my case could actually be 30 minutes or 2 hours) was just not that important to me. As long as I could use the laptop for 3-4 hours on battery, I would be fine. But thats me.

Can I ask what tasks could take off 2 hours?! I guess at that point we're talking about pushing the machine hard enough that, whether you had the i5 or i7, you'd want to plug it in? Certainly not work that you'd consider doing on the battery, I presume?

ZBoater · Aug 24, 2013

lamboman said:
Can I ask what tasks could take off 2 hours?! I guess at that point we're talking about pushing the machine hard enough that, whether you had the i5 or i7, you'd want to plug it in? Certainly not work that you'd consider doing on the battery, I presume?

Correct. Even in the Anandtech article they mention the unlikelihood of running tasks that would push the CPU so hard for so long. In my case, I only got 3 hours of battery playing Civilization 5 and that was the Mac version (not VM). Civ5 is extremely CPU intensive.

The applications I run in VM are MS Office, Quicken, and some utilities I may run for a few minutes and that's it. I would imagine that ripping a DVD, encoding video, or other things you could do for hours would cause a problem, but those are very rare. Games are more likely to be common things you run for hours and hours and that take up a lot of battery. If you run Windows games in VM, Windows is not as battery efficient as OS X, so those may be applications that may show the greatest battery difference.

Civ5 is the only game recently I've played for hours. Most other games I may play for 1 hour at most. I may spend more hours surfing the internet or working on MS Office, neither of which will make much of a difference batterywise.

Enrico · Aug 24, 2013

I'm about to order the i5/8/256 but your reports of it being sluggish just by browsing the net, scare me!
Is it something you have not noticed on the i7 machine? Does it feel faster even doing basic things?
I will be using Parallels Win8 VM aswell, only for MS Office suite.

ZBoater · Aug 24, 2013

Enrico said:
I'm about to order the i5/8/256 but your reports of it being sluggish just by browsing the net, scare me!
Is it something you have not noticed on the i7 machine? Does it feel faster even doing basic things?
I will be using Parallels Win8 VM aswell, only for MS Office suite.

I have not compared myself the i5 to the i7, but I have read posts from other people who have any reported stuttering and slugishness. It's almost impossible to independently verify, but Anandtech has a very good comparison, the the i7 has a significant performance advantage over the i5. From their review:

"Oh man, the Core i7 upgraded seriously fixes everything. We get near perfect scaling here, showing a massive 27% increase in performance over the default Core i5 1.3GHz setup. The single threaded performance of the upgraded 13-inch MacBook Air is almost able to equal that of the 15-inch MacBook Pro with Retina Display. "

http://www.anandtech.com/show/7113/2013-macbook-air-core-i5-4250u-vs-core-i7-4650u/2

So my advice is that unless budget is tight, spring for the i7. You will be getting the top of the line processor option, so when and if you do get a stutter or a slowdown, you will never have to second guess yourself on whether you didn't get enough CPU. YMMV.

dyn · Aug 24, 2013

The i7 is more powerful which comes with a cost: it uses more power and will get hotter quicker. The MBA has a certain envelope when it comes to heat. Anandtech talks about this in their review about the 13" MBA. The i7 will hit the envelop sooner than the i5 and when it does it will throttle back. Reason why in some cases the i7 isn't as powerful.

VM's also have almost no benefit from that i7 compared to the i5. They only have a benefit when you require a fast cpu in the vm in which case the MBA is simply the wrong tool (you should be using the MBP, either the normal one (preferably with ssd) or the retina one). All in all the upgrade to the i7 does not make much sense. Either get the i5 or a MacBook Pro if you need the cpu power (they are designed for the faster cpus).

ZBoater · Aug 24, 2013

dyn said:
... The MBA has a certain envelope when it comes to heat. Anandtech talks about this in their review about the 13" MBA. The i7 will hit the envelop sooner than the i5 and when it does it will throttle back. Reason why in some cases the i7 isn't as powerful.

Would you mind quoting where the review says this? I think I missed it.

dyn said:
VM's also have almost no benefit from that i7 compared to the i5. They only have a benefit when you require a fast cpu in the vm in which case the MBA is simply the wrong tool ....

Sorry, I must have missed that memo. The MBA is a fine tool to run VMs...

lamboman · Aug 24, 2013

Finally got sick of researching into a question that ultimately nobody could conclusively answer. Battery life figures from other machines suggest that the i7 could take quite a battery hit compared to the i5. Personally, I prioritise the latter, so the i5 is my choice now

ZBoater said:
I have not compared myself the i5 to the i7, but I have read posts from other people who have any reported stuttering and slugishness. It's almost impossible to independently verify, but Anandtech has a very good comparison, the the i7 has a significant performance advantage over the i5. From their review:

"Oh man, the Core i7 upgraded seriously fixes everything. We get near perfect scaling here, showing a massive 27% increase in performance over the default Core i5 1.3GHz setup. The single threaded performance of the upgraded 13-inch MacBook Air is almost able to equal that of the 15-inch MacBook Pro with Retina Display. "

http://www.anandtech.com/show/7113/2013-macbook-air-core-i5-4250u-vs-core-i7-4650u/2

So my advice is that unless budget is tight, spring for the i7. You will be getting the top of the line processor option, so when and if you do get a stutter or a slowdown, you will never have to second guess yourself on whether you didn't get enough CPU. YMMV.

Don't want to get into the debate too much, however that is a single benchmark that represents the i7's biggest advantage. For basic web browsing and productivity work, you aren't always going to see the performance benefits of the i7 (sitting with a Word document open and typing won't make a difference in the slightest, for example!). Even if you do (the whole UI responsiveness debate with the i5), it may not be worth it for that individual user. I'm still not entirely convinced that the i5 isn't slightly more sluggish than the i7, but that's a sacrifice I'm willing to make.

ZBoater said:
Sorry, I must have missed that memo. The MBA is a fine tool to run VMs...

He meant if you need serious power, not just for basic VM usage.

ZBoater · Aug 24, 2013

lamboman said:
...For basic web browsing and productivity work, you aren't always going to see the performance benefits of the i7 (sitting with a Word document open and typing won't make a difference in the slightest, for example!). Even if you do (the whole UI responsiveness debate with the i5), it may not be worth it for that individual user. I'm still not entirely convinced that the i5 isn't slightly more sluggish than the i7, but that's a sacrifice I'm willing to make.

Of course both machines at or near idle will behave the same. However I am not as quick to dismiss those who have compared them side by side in terms of UI responsiveness. But if that is a sacrifice you are willing to make, then that works for you, and that is what matters in your purchase decision.

lamboman said:
He meant if you need serious power, not just for basic VM usage.

Well, as a habit I tend to avoid reading people's mind and assuming they type one thing and mean another. If you need "serious" power, then yes, by all means, a quad-core is in your future. But the i7 MBA is plenty capable of "serious" work. Whatever that is.

lamboman · Aug 25, 2013

ZBoater said:
Of course both machines at or near idle will behave the same. However I am not as quick to dismiss those who have compared them side by side in terms of UI responsiveness. But if that is a sacrifice you are willing to make, then that works for you, and that is what matters in your purchase decision.

Exactly

ZBoater said:
Well, as a habit I tend to avoid reading people's mind and assuming they type one thing and mean another. If you need "serious" power, then yes, by all means, a quad-core is in your future. But the i7 MBA is plenty capable of "serious" work. Whatever that is.

It's actually what he said. In all fairness of you will be doing extremely intensive projects (eg. 3D modelling under a VM, for whatever reason), the MBA isn't the ideal machine.

ZBoater · Aug 25, 2013

lamboman said:
...It's actually what he said...

No. What he said was

VM's also have almost no benefit from that i7 compared to the i5. They only have a benefit when you require a fast cpu in the vm in which case the MBA is simply the wrong tool (you should be using the MBP, either the normal one (preferably with ssd) or the retina one).

And I quoted it in my reply. If he meant something else he should have typed that.

dyn · Aug 25, 2013

ZBoater said:
Would you mind quoting where the review says this? I think I missed it.

It's a bit scattered over the review so some quotes:

The lower base clock alone shouldnt mean much, but the max TDP of the CPUs in the new MacBook Air falls as well - from 17W down to 15W. The thermal limit is even more dramatic since with Haswell ULT, the 15W includes the CPU/GPU as well as the on-package PCH. In Ivy Bridge the PCH was off package and wasnt included in the 17W TDP.

Max turbo clocks are identical between the Haswell ULT CPUs Apple picked this round and the Ivy Bridge models before, but with a lower TDP itll be harder to always sustain the same frequencies given the right workload.

However, Haswell has some nice features to compensate for it:

Haswell does feature a not insignificant gain in IPC compared to Ivy Bridge, which should help offset the power constraints that could otherwise force a larger regression in performance.

As we found in our initial look at the new MBA, the 1.3GHz Core i5 CPU ends up performing about the same as last year's 1.8GHz part. I'd like to say it's all because of cooling and turbo boost, but in all likelihood Apple is trading some of Haswell's IPC gains for frequency here - enabling identical performance, at lower clocks thanks to Haswell's more efficient architecture.

And there's also this:

The 13-inch 1.3GHz Core i5 configuration performs similarly to last year's 11-inch 1.7GHz config. It's an interesting comparison because the 11-inch 2012 model is more thermally constrained than the 13-inch 2012 model, which is exactly what we see when we compare the 2013 13-inch MBA to the 2012 13-inch MBA.

Regarding the gpu the thermal discussion returns:

Similar to the CPU discussion, on the GPU front Haswell has to operate under more serious thermal limits than with Ivy Bridge. Previously the GPU could take the lions share of a 17W TDP with 16 EUs, now it has 15W to share with the PCH as well as the CPU and 2.5x the number of EUs to boot. As both chips are built on the same 22nm (P1270) process, power either has to go up or clocks have to come down. Intel rationally chose the latter.

If you match this with the i5 vs i7 article things become more clear.

Sorry, I must have missed that memo. The MBA is a fine tool to run VMs...

No you haven't missed the memo, you have missed my point. Running vm's does not require a fast cpu. Running vm's requires lots of memory and fast I/O (i.e. an ssd). The cpu and gpu do not matter that much (usually the Core Duo and Intel GMA950 in the first MacBook will be more than adequate). They'll matter only when you run a vm that requires such power. For example a vm running Windows with Visual Studio Pro that you use for compiling or when you want to run a 3d game in the vm. For the former you need the cpu power, for the latter you need the gpu power. In this case the cpu and gpu in the MBA may not be enough, especially the gpu. In that case the MBA isn't the proper tool, you should upgrade to the MBP with the more powerful Nvidia gpu.

lamboman said:
He meant if you need serious power, not just for basic VM usage.

I actually meant the vm but it is something that you can apply to the entire machine as well. Simply put: the MBA is a nice mobile device with a lot of power. Enough to run vm's properly. It is not suited for people who require a fast cpu and/or gpu, for that Apple has the 15" MBP and 15" MBP Retina (or the 13" version if you only need a fast cpu). Upgrading to the i7 because you need power is just silly due to the thermal envelope (it's a very thing device; the MBP is much thicker and more able to get rid of heat) and the i7 cpu that is available. The cpu and gpu options in the MBP series are much more suited for such people.

Or in other words: you don't need the i7, the i5 is fast enough and the difference between them is too small. If you really need more than that get the MBP. The difference is much bigger.

ZBoater · Aug 25, 2013

dyn said:
It's a bit scattered over the review so some quotes:

Wow, scattered is an understatement. I don't mean to be difficult, but to go from

dyn said:
The i7 will hit the envelop sooner than the i5 and when it does it will throttle back. Reason why in some cases the i7 isn't as powerful.

To the whole bunch of scattered quotes you posted is quite a stretch. I just don't find the correlation between those quotes and the statement that the "in some cases i7 isn't as powerful" because of heat throttling. Are there some benchmark results to back that up? I just don't see that, and I re-read it three times. I must be blind.

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