Re: [PATCH 0/3] PTI for x86-32 Fixes and Updates

[Andy Lutomirski]

> On Jul 24, 2018, at 6:39 AM, Pavel Machek <pavel@xxxxxx> wrote:
> 
>> On Mon 2018-07-23 12:00:08, Linus Torvalds wrote:
>>> On Mon, Jul 23, 2018 at 7:09 AM Pavel Machek <pavel@xxxxxx> wrote:
>>> 
>>> Meanwhile... it looks like gcc is not slowed down significantly, but
>>> other stuff sees 30% .. 40% slowdowns... which is rather
>>> significant.
>> 
>> That is more or less expected.
> 
> Ok, so I was wrong. bzip2 showed 30% slowdown, but running test in a
> loop, I get (on v4.18) that, too.
> 
> 

...

The obvious cause would be thermal issues, which are increasingly common in laptops.  You could get cycle counts from perf stat, perhaps.