
Microsoft: Haswell and older CPUs are slowed down significantly by Spectre fixes - bhouston
https://hothardware.com/news/microsoft-windows-10-pcs-haswell-intel-cpus-significant-slowdowns-post-spectre-patch
======
jesperhh
How convenient for Intel - they have been unable to improve significantly on
the single threaded performance since the 4790K but with this "fix", newer
CPUs will magically start to look better than the old ones..

~~~
dogma1138
Let’s see what happens with AMD.

It’s vulnerable to Spectre even to Variant 2 but they define it as a very low
risk what ever that means and only issuing fixes for Variant 1.

It looks like the second variant of Spectre the out of bounds check is the
culprit here; if AMD isn’t vulnerable at all it would be great but to me it
looks like they are sitting on the fence to wait and see where the exploits
go.

------
have_faith
Do Microsoft etc see this as an opportunity in disguise perhaps? A problem out
of their hands, that's not their fault, that might make people think about
upgrading their machines. And the best bit is that it also effects your
competitors.

~~~
mehrdadn
I was thinking exactly the same thing, but regarding the OS rather than
machines. It's their best excuse for making everyone upgrade to Windows 10.

~~~
cm2187
I don't think Windows runs faster than Windows 7. It's only by forcing people
to upgrade their machine that Microsoft will manage to force people to give up
7 for 10.

~~~
chrisper
Windows 10 is faster than Windows 7:

>Older versions of Windows have a larger performance impact because Windows 7
and Windows 8 have more user-kernel transitions because of legacy design
decisions, such as all font rendering taking place in the kernel.

From:
[https://cloudblogs.microsoft.com/microsoftsecure/2018/01/09/...](https://cloudblogs.microsoft.com/microsoftsecure/2018/01/09/understanding-
the-performance-impact-of-spectre-and-meltdown-mitigations-on-windows-
systems/)

~~~
tomsmeding
Font rendering taking place in the kernel does indeed look _quite_ like a
legacy design decision.

~~~
cremno
It's also kinda ironic because improved performance was the reason behind that
decision.

~~~
mehrdadn
To be honest it might still have better performance if/when they add more
mitigations for more security vulnerabilities. It seems like an anomaly right
now since they're only addressing Meltdown/Spectre, but the core issues (no
pun intended) are fundamentally there.

------
mcintyre1994
> This means the typical home and business PC user should not see significant
> slowdowns in common tasks such as reading email, writing a document or
> accessing digital photos.

How can Intel possibly continue to claim this when the majority of home and
business PC users are on Windows, and probably mostly on hardware older than
Skylake too?

~~~
dspillett
For most of those users the affected part of the system is not a key
bottleneck: syscalls such as filesystem or hardware access.

For most home/office tasks (web browsing, email, office documents) most of the
time is spent waiting for user input or network responses. Even on a really
slow old Atom-based netbook I suspect that the difference will be at worst
"noticeable" and not significant for these tasks (i.e. it isn't going to make
any difference while the app is waiting for your next key-press).

Older games that make many small calls to the graphics hardware will be
affected but unless you are running them on really old hardware you'll not
notice that either as they won't tax newer hardware even with the extra work.
Newer games will be using more efficient techniques anyway.

Startup times are likely to be affected, both OS and individual application,
but that is generally a once-per-session matter, and of course there will be
some applications (or some workflows using applications otherwise relatively
unaffected) that will see a difference, but not the majority.

Older OSs may be more starkly affected because of design changes since. For
instance until 10 Windows performed font parsing and rendering in the kernel
so text heavy applications might see some extra display lag after these
patches. Low-memory situations might be more affected too, as RAM starvation
increases the amount of IO happening during normal operation.

Developers are far more likely to notice, I've seen some bad before/after
benchmarks for build processes. Long-running tasks, particularly those
performing IO such as video encoding, are more likely to make the differences
visible too (10% extra on a many-hour encoding task could add up to something
pretty inconvenient). It is expected that certain server loads are going to be
the worst hit. But none of this paragraph's "things that will be affected" are
typical home/business use cases for the majority.

------
grumpopotamus
Haswell and older will see more-significant slowdowns, Skylake and newer will
see less-significant slowdowns... what about Broadwell? I have a 6850k.

~~~
chrisper
6850k has launch date 2016. So you are fine.

Microsoft claims CPUs post 2015 only have unnoticable slowdown.

~~~
cMax347
I have a i7 5500 so I am also interested in this. Broadwell is a shrink of
Haswell (22nm->14nm), a "tick" in intel terminology. So Broadwell users might
not be that lucky?

------
Tempest1981
Was hoping to see some benchmarks, or at least rough percentages. Sounds like
vague marketing-speak.

All I really know is that it won't be faster--thanks.

------
dvfjsdhgfv
The wording re. the difference between Windows 10 and 7 seems intriguing:

> Windows 10 PCs with Haswell or older processors will see "more significant
> slowdowns" and Microsoft notes that a segment of customers may "notice a
> decrease in system performance”. > Windows 7 and Windows 8 PCs powered by
> Haswell or older processors will see a "decrease in system performance" for
> "most users".

Does it mean that if you care about performance, it's better to use Windows 7
instead of 10? It's not spelled out explicitly, but they way they worded it
suggests so.

~~~
Shoothe
The original post offers some more details on this matter:

> For context, on newer CPUs such as on Skylake and beyond, Intel has refined
> the instructions used to disable branch speculation to be more specific to
> indirect branches, reducing the overall performance penalty of the Spectre
> mitigation. Older versions of Windows have a larger performance impact
> because Windows 7 and Windows 8 have more user-kernel transitions because of
> legacy design decisions, such as all font rendering taking place in the
> kernel. We will publish data on benchmark performance in the weeks ahead.

Source:
[https://cloudblogs.microsoft.com/microsoftsecure/2018/01/09/...](https://cloudblogs.microsoft.com/microsoftsecure/2018/01/09/understanding-
the-performance-impact-of-spectre-and-meltdown-mitigations-on-windows-
systems/)

