Musing #48: Impact of Spectre/Meltdown patch (With Intel's March Microcode Update)


Spectre and Meltdown have been all over the news in the past few days. While the seriousness of the bug cannot be understated, the speculation on the performance impact of the patch, especially on older processors, has been particularly worrisome. Google and Intel have put forth some assurances, but the end result is yet to be seen.

As my desktop is equipped with the generations-old i5-3470, I have to brace for whatever performance degradation comes with the patch. Unfortunately, with ASRock having released the last BIOS update for my motherboard in 2013, one can only hope to receive an official update. For the time being, the only option is to rely on Microsoft's Windows 10 patch which only partially mitigates this issue.

Even then, it offers a first glimpse at the performance that has to be scarified in lieu of security. Intel has stated that the impact will vary based on the task and hence there is no easy way to determine the impact of the patch. I went with Cinebench R15 and CrystalDiskMark to quickly capture the impact on some everyday tasks.

As can be seen in the screenshot below, the performance impact seems to be quite significant with the post-patch score being nearly 7% lower. This is by all means a huge impact and cannot be disregarded.

Tutorial #11: Thermal control of Core M 5Y10 (Broadwell)

The first generation Core M was an engineering marvel in terms of the power it managed to fit within the 4.5W TDP envelope. In terms of performance, it sat somewhere in between the 5th generation U-series Core i3 and i5 which bear TDP of 15W but blew both of them out of the water when it came to efficiency. The fanless design not only cut down the weight of the tablet but in fact removed a significant point of failure. My gut feeling is that whirring fans are not a good fit for use cases which involve significant movement à la tablets. On the flip side, the processor package is nothing short of a toaster with its sky high temperature under sustained full load.

This led me to fire up Intel's Extreme Tuning Utility (XTU) on my Dell Venue 11 Pro 7140. Normally, devices in a portable form factor like tablets and laptops leave very constrained thermal dissipation and hence are not good tuning candidates. Hence, unsurprisingly, only the voltage and turbo power controls are on offer in the case of the Core M. After trying out over two dozen profiles, I settled on the following three detailed in the table below wherein I have listed the changes made to the default (reference) settings. Profile 1 aims at a temperature of mid-60s under turbo boost which is akin to what you may find in fanned processors. Profile 2 has turbo boost set to the TDP and allows for sustained usage without thermal throttling. Profile 3 on the other hand is the default profile but with stable under-volting that reduces the temperature just enough to limit instances of thermal throttling under sustained full load.


To check the impact of these profiles, I have used the benchmark within XTU (XMarks) as well as the CPU stress test (duration of 1 min). Additionally, I have used the CPU Mark and 3D Mark tests of PassMark as they seemed to be particularly responsive to the changes. Lastly, any CPU test would be incomplete without CPU-Z and hence its bench also makes an appearance.


As can be seen from the table above, there is a compromise to be made between temperature and performance depending on what floats your boat. In my case, I decided to go with 'Profile 3' for now since sacrificing power in a mobile device is always a tough choice. Even then, it is an improvement over the default profile in terms of performance as well as temperature. Profile 2 seems like an especially good option in case thermal throttling is a major concern while Profile 1 plays it really cool if you cant't warm up to the idea of using the tablet as a finger heater. Overall, I am to this day impressed by the Core M package, enough to have it don a triple avatar.

Review #30: Dell Tablet Keyboard - Mobile for Venue 11 Pro (AliExpress)

I have been using the Dell Venue 11 Pro 7140 as a tablet for over a year and a half now and it has been a faithful companion. May be I will do a retrospective review on it sometime in the future, but for now the review is focussed on one of its accessories which I would argue is the most compelling one - the keyboard dock with a built-in battery. It completes the transformation of the tablet to a full fledged laptop, albeit one of compact proportions while giving a significant bump to the battery life.

As was the case when I purchased the tablet, I had to look overseas for the keyboard dock. I was ready to settle for a refurbished one since price as well as availability is a concern when purchasing an accessory for a device that is over 2 years old. Amazon.com had it listed at $160 (now at $110) and even then it wasn't available for shipping to India. Using third-party shipping services would have meant an expense close to at least $250, an option that wasn't worth considering. Hence, as always, it was time to take recourse to the fail-safe which more often than not happens to be AliExpress and sure enough it didn't disappoint.

While there were no "brand new" ones available, in true Chinese style, the products were listed as 99% new, 95% new, 90% new and 80% new with prices ranging from $55-70. The only way to relate this "newness" was through the pictures and since I wanted it to be as new as possible, I went with the 99% new option. Shipping of the product was not immediate and took 5 days, but thereafter the product was received within a month which is the standard time frame for delivery to India. I was a bit skeptical of using the Seller's shipping method but it turns out that the one used by the seller - Bpost International, is a dependable one.

If I were to attribute the "99% newness" to the looks alone, then I would say the description was right on the mark. There were no visible scratches on the product and it looked as good as new. The dock was immediately recognized on connection and the "Battery 2" percentage was immediately visible as being fully charged. My kitchen scale with its fairly generous margin of error puts the weight of the keyboard dock at 681g, a shade lesser than the tablet itself which weighed in at 717g. In practical terms, the keyboard dock needs to weigh as much as the tablet or else it would simply tip over. Thus, at 1.4 kg, this isn't perhaps the most lightweight laptop for its form factor, but it comes with the advantage of having dual batteries and a detachable touch screen.


My only disappointment with the purchase was that the 99% newness didn't apply to the battery within the keyboard dock. On first connection, I could see that the battery health was reported as less than 80% within the Dell Diagnostics utility and had thus already undergone a lot of discharge cycles. I have posted the current battery stats below which indicates that the full charge capacity of the battery dock compared to the design capacity is similar to the tablet battery which is over 18 months old. I guess I can't complain much in terms of the price I had paid compared to a new one but the post on AliExpress seems to be lacking in this regard.


As can be seen from the above battery stats, the dock adds about 70% of the tablet's battery capacity which translates well as far as battery life is concerned. It is difficult to pinpoint the combined battery life as it varies wildly depending on the use case scenario but the following stats should give an indication of what to expect. If watching Full HD videos encoded in H.264 is you primary use case, then you can expect the battery to last about 4 movies and a bit.


Moving on to the keyboard aspect of the dock, since the keyboard has to follow the tablet's form factor, the wide aspect ratio ensures that there is enough width available for the keys. Typing on this keyboard is a good experience and doesn't require any adjustments with respect to typing on an external keyboard. It is a bit odd to have the function keys as secondary but at the same time it is more practical as one is more likely to adjust the brightness and volume compared to the "F" keys. The wide aspect ratio on the flip side limits the height of the trackpad which is quite observable when scrolling. However, the trackpad itself is quite good and supports all the Windows 10 gestures out of the box like scrolling, zooming, app switching and minimizing to desktop. The only disappointment might be that the dock itself doesn't come with additional ports, though that would also mean losing connection to the USB devices when detached. Considering this is a tablet first, the decision seems practical enough.

On the whole, I am extremely pleased with the purchase as this "laptop" now perfectly complements my desktop, with the tablet completing a virtuous troika.