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Subject: Re: [PATCH 0/3] PTI for x86-32 Fixes and Updates
From:   Andy Lutomirski <luto@amacapital.net>
In-Reply-To: <20180724133935.GA30797@amd>
Date:   Tue, 24 Jul 2018 07:39:38 -0700
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Joerg Roedel <joro@8bytes.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@kernel.org>, Peter Anvin <hpa@zytor.com>,
        the arch/x86 maintainers <x86@kernel.org>,
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        Borislav Petkov <bp@alien8.de>, Jiri Kosina <jkosina@suse.cz>,
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        Brian Gerst <brgerst@gmail.com>,
        David Laight <David.Laight@aculab.com>,
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        Eduardo Valentin <eduval@amazon.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
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        "Liguori, Anthony" <aliguori@amazon.com>,
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        Jiri Olsa <jolsa@redhat.com>,
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References: <1532103744-31902-1-git-send-email-joro@8bytes.org> <20180723140925.GA4285@amd> <CA+55aFynT9Sp7CbnB=GqLbns7GFZbv3pDSQm_h0jFvJpz3ES+g@mail.gmail.com> <20180724133935.GA30797@amd>
To:     Pavel Machek <pavel@ucw.cz>
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> On Jul 24, 2018, at 6:39 AM, Pavel Machek <pavel@ucw.cz> wrote:
>=20
>> On Mon 2018-07-23 12:00:08, Linus Torvalds wrote:
>>> On Mon, Jul 23, 2018 at 7:09 AM Pavel Machek <pavel@ucw.cz> wrote:
>>>=20
>>> Meanwhile... it looks like gcc is not slowed down significantly, but
>>> other stuff sees 30% .. 40% slowdowns... which is rather
>>> significant.
>>=20
>> That is more or less expected.
>=20
> Ok, so I was wrong. bzip2 showed 30% slowdown, but running test in a
> loop, I get (on v4.18) that, too.
>=20
>=20

...

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