Meltdown's Impact on Storage Performance - Really an Issue?

Subject: Storage | January 5, 2018 - 08:45 PM |
Tagged: RS4, RS3, patch, meltdown, KB4056892, cpu, 960 EVO, 900P, 850 EVO

While the Meltdown announcements and patches were in full swing, I was busily testing a round of storage devices to evaluate the potential negative impact of the Meltdown patch. Much of the testing we've seen has come in the form of Linux benchmarks, and today we saw a few come out on the Windows side of things. Most of the published data to date shows a ~20% performance hit to small random accesses, but I've noted that the majority of reviewers seem to be focusing on the Samsung 950/960 series SSDs. Sure these are popular devices, but when evaluating changes to a storage subsystem, it's unwise to just stick with a single type of product.

Test conditions were as follows:

  • ASUS Prime Z270-A + 7700K
    • C-States disabled,  no overclock.
    • ASUS MCE disabled, all other clock settings = AUTO.
  • SSDs:
    • Intel Optane 900P 480GB (Intel NVMe driver)
    • Samsung 960 EVO 500GB (Samsung NVMe driver)
    • Samsung 850 EVO 500GB (Intel RST driver)
  • Conditioning:
    • NTFS partition.
    • 16GB test file. Sequential conditioning.
    • Remainder of SSD sequentially filled to capacity.

The first results come from a clean Windows Redstone 3 install compared to a clean Windows 10 Redstone 4 (build 17063), which is a fast ring build including the Meltdown patch:


The 960 EVO comes in at that same 20% drop seen elsewhere, but check out the 850 EVO's nearly 10% *increase* in performance. The 900P pushes this further, showing an over 15% *increase*. You would figure that a patch that adds latency to API calls would have a noticeable impact on a storage device offering extremely low latencies, but that did not end up being the case in practice.

Since the 960 EVO looked like an outlier here, I also re-tested it using the Microsoft Inbox NVMe driver, as well as by connecting it via the chipset (which uses the Intel RST driver). A similar drop in performance was seen in all configurations.

The second set of results was obtained later, taking our clean RS3 install and updating it to current, which at the time included the Microsoft roll-up 01-2018 package (KB4056892):


Note that the results are similar, though Optane did not see as much of a boost here. It is likely that some specific optimizations have been included in RS4 that are more beneficial to lower latency storage devices.

As a final data point, here's what our tests look like with software polling implemented:


The above test results are using an application method that effectively bypasses the typical interrupt requests associated with file transfers. Note that the differences are significantly reduced once IRQs are removed from the picture. Also note that kernel API calls are still taking place here.

Well there you have it. Some gain and some lose. Given that a far lower latency device (900P) sees zero performance hit (actually gaining speed), I suspect that whatever penalty associated with Meltdown could be easily optimized out via updates to the Windows Inbox and Samsung NVMe drivers.

Damned if you do, damned if you don't. Meltdown and Spectre keep getting worse

Subject: General Tech | January 5, 2018 - 02:22 PM |
Tagged: Intel, spectre, meltdown, antivirus, security, KB4056892

Microsoft are now pushing out an update to mitigate some of the security issues that Meltdown takes advantage of, but there is a small problem.  KB4056892 may cause your machine to BSoD depending on the anti-virus software you use so it is not recommended you install the update manually.  Windows Update looks for a registry entry on your machine, which indicates your AV software has updated and is compatible with the patch, so far Symantec, F-Secure, Avast, and Windows Defender have all updated.  If you are curious, The Register has posted the key in this story so you can check for yourself if you are ready to update and make the change if not.

It is something you should be doing soon, as this is a serious vulnerability which is only somewhat mitigated by the patch but at least this attack will not be successful.


"Microsoft has released updates for Windows to block attempts by hackers and malware to exploit the Meltdown vulnerability in Intel x86-64 processors – but you will want to check your antivirus software before applying the fixes."

Here is some more Tech News from around the web:

Tech Talk

Source: The Register