The 2013 MacBook Air Review (13-inch)
by Anand Lal Shimpi on June 24, 2013 12:01 AM ESTPCIe SSD Performance
I created a Boot Camp partition of around 120GB and ran our client iometer benchmarks to put the new PCIe SSD’s performance in perspective.
Peak random read performance is roughly comparable to the previous-generation Samsung controller. Random write performance took a bit of a hit but it's still more than fast enough for client workloads. Sequential speeds are much improved but the gains are really only visible at high queue depths. Low queue depth sequential transfers can’t be split up enough in order to really require PCIe.
What does this mean in the real world? The new SSD is definitely snappier in system use. Wake from sleep is a bit quicker, as are application launches. The funny thing is that with the exception of high-speed Thunderbolt arrays, most external sources aren’t fast enough to even stress the new storage subsystem in the MacBook Air. Large file copies confined to the drive itself benefit a bit as well. I saw roughly 300MB/s reads and 300MB/s writes when copying a large dmg from/to the MacBook Air’s PCIe SSD (compared to roughly 200/200MBps on the old Samsung SATA SSD from the rMBP15).
If you have an external Thunderbolt array with at least a couple of drives, you should have no issues matching the MBA’s internal SSD performance.
Seeing as how this is our first experience with Samsung’s PCIe SSD controller, I wanted to get a feel for how the drive behaved under extended high queue depth random writes. I ran a modified version of our IO consistency test. The test was modified to run in a 91GB space on the MBA’s Boot Camp partition. I made sure to fill the rest of the drive completely, but the random writes were effectively constrained to 91GB of LBAs. When I get back from the UK I’m going to try setting up an external boot drive and will do some more extensive testing on the drive.
The IO consistency results, at least within a somewhat constrained space actually look really good. I have a feeling that Samsung might have improved its IO consistency story with this generation, but I’ll wait on saying for sure until I’ve had a chance to do some more work with the controller. For the vast majority of users however, solid random write performance like this over a 91GB space on a full drive is actually very good news.
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seapeople - Tuesday, June 25, 2013 - link
Brightness is pretty much the number one power consumer in a laptop like this (which is actually mentioned in the review). If you expect to run anything at 100% brightness and get anywhere near ideal battery life then you are bound to be disappointed.name99 - Monday, June 24, 2013 - link
"802.11ac ... better spatial efficiency within those channels (256QAM vs. 64QAM in 802.11n). Today, that means a doubling of channel bandwidth and a 4x increase in data encoded on a carrier"This is a deeply flawed statement in two ways.
(a) The modulation form describes (essentially) how many bits can be packed into a single up/down segment of a sinusoid wave form, ie how many bits/Hz. It is constrained by the amount of noise in the channel (ie the signal to noise ratio) which smeers different amplitudes together so that you can't tell them apart.
It can be improved somewhat over 802.11n performance by using a better error correcting code (which essentially distributes the random noise level over a number of bits, so that a single large amount of noise rather than destroying that bit information gets spread into a smaller amount of noise over multiple bits).
802.11ac uses LDPC, a better error correcting code, which allows it to use more aggressive modulation.
Point is, in all this the improved modulation has nothing to do with spatial encoding and spatial efficiency.
(b) The QAM64 and QAM256 refer to the number of possible states encoded per bit, not in any way to the number of bits encoded. So QAM64 encodes 6 bits per Hz, QAM256 encodes 8 bits per Hz. the improvement is 8/6=1.33 which is nice, but is not "a 4x increase in data encoded on a carrier".
We are close to the end of the line with fancy modulation. From now on out, pretty much all the heavy lifting comes from
(1) wider spectrum (see the 80 and 160MHz of 802.11ac) and
(2) smaller, more densely distributed base stations.
We could move from 3 up to 4 spatial streams (perhaps using polarization to help out) but that's tough to push further without much larger antennas (and a rapidly growing computational budget).
There is one BIG space for a one-time 2x improvement, namely tossing the 802.11 distributed MAC, which wastes half the time waiting randomly for one party or another to talk, and switching to a centrally controlled MAC (like the telcos) along with a very narrow RACH (random access channel) for lightweight tasks like paging and joining.
My guess/hope is that the successor to 802.11ac will consist primarily of the two issues I've described above (and so will look a lot more like new SW than new DSP algorithms), namely a central arbiter for a network along with the idea that, from the start, the network will consist of multiple small low-power cells working together, about one per room, rather than a single base station trying to reach out to 100 yards or more.
bittwiddler - Monday, June 24, 2013 - link
• The keyboard key size and spacing is the same on the 11 and 13" MBAs.• The 11" MBA is exempt from being removed from luggage during TSA screenings, unlike the 13.
• The 11" screen is lower height than most and doesn't get caught by the clip for the airplane seat tray table.
• When it comes to business travel computing, I'm not interested in a race to the bottom.
Sabresiberian - Monday, June 24, 2013 - link
One thing I would NOT like is for Apple to make a move to a 16:9 screen. I'd certainly rather have 1440x900 on a 13" screen than anything denser that was 16:9. I mean, I'm one of the guys that has been harping on pixel density and refresh rates since before we had modern smart phones (the move to LCDs set us back a decade or more in that regard), but on a screen smaller than 27", 16:9 is just bad. In my not-so-humble opinion.4:3 is better for something smaller than 17", but I can live with 16:10. :)
Kevin G - Monday, June 24, 2013 - link
Re-reading trough the review I have a question about the display: does it use panel self refresh? I recall Intel hyping up this technology several years ago and the Haswell slides in this review indicate support for it. The question is, does Apple take advantage of it?Kevin G - Monday, June 24, 2013 - link
I think that I can answer my own question. I couldn't find the data sheet for the review panel LSN133BT01A02 but references on the web point towards an early 2012 release for it. Thus it looks like it appeared on the market before panel self refresh was slated for wide spread introduction alongside Haswell.hobagman - Monday, June 24, 2013 - link
Hi Anand & all -- could I ask a more CPU related question I've been wondering about a lot -- how come the die shots always look so colorful and diverse, when isn't the top layer all just interconnects? Or are the die shots actually taken before they do the interconnects, consisting in the top 10-15 layers? Would really appreciate an explanation of this ...hobagman - Monday, June 24, 2013 - link
I mean, what are we actually seeing when we look at the die shot? Are those all different transistor regions, and if so, we must be looking at the bottom layers. Or is it that the interconnects in the different regions look different ... or ... ?SkylerSaleh - Tuesday, June 25, 2013 - link
When making the ASIC, thin layers of glass are grown on the silicon, etched, and filled with metal to build the interconnects. This leaves small sharp geometric shapes in the glass, which reacts with the light similarly to how a prism would, causing the wafer to appear colorful.cbrownx88 - Monday, June 24, 2013 - link
Please please please revisit with the i7 config - been wanting to make a purchase but have been waiting for this review (and now waiting on the update lol).