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From: Arjan van de Ven <arjan@linux.intel.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>,
	Noah Goldstein <goldstein.w.n@gmail.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86-ml <x86@kernel.org>, lkml <linux-kernel@vger.kernel.org>
Subject: Re: [GIT PULL] x86/misc for 6.5
Date: Tue, 27 Jun 2023 15:50:48 -0700	[thread overview]
Message-ID: <51f58d51-d5bf-79a2-a32a-e6849a118123@linux.intel.com> (raw)
In-Reply-To: <CAHk-=wgMw2VE8afWp4p6RyJKCvnkhNXx4XUByUOHUWKiAo=WLQ@mail.gmail.com>

On 6/27/2023 3:43 PM, Linus Torvalds wrote:
> On Tue, 27 Jun 2023 at 15:25, Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
>>
>> I don't know what the rules are - and some of the functions you test
>> seem actively buggy (ie not handling alignment right etc).
> 
> Oh. And you *only* test the 40-byte case. That seems a bit bogus.
> 
> If I change the packet size from 40 to 1500, I get
> 
>    02: 185.1 / 186.4 cycles (8b414316) Upcoming linux kernel version
>    04: 184.9 / 186.5 cycles (8b414316) Specialized to size 40
>    06: 107.3 / 117.2 cycles (8b414316) New version
>    22: 185.6 / 186.5 cycles (8b414316) Odd-alignment handling removed
> 
> which seems unexpectedly bad for the other versions.
> 

I'm not surprised though; running 2 parallel streams (where one stream has a fixed zero as input,
so can run OOO any time) .. can really have a performance change like this


  reply	other threads:[~2023-06-27 22:50 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-27 11:00 [GIT PULL] x86/misc for 6.5 Borislav Petkov
2023-06-27 20:11 ` Linus Torvalds
2023-06-27 20:26   ` Linus Torvalds
2023-06-27 20:38     ` Borislav Petkov
2023-06-27 20:49       ` Linus Torvalds
2023-06-27 21:11         ` Borislav Petkov
2023-06-27 21:44         ` Linus Torvalds
2023-06-27 21:58           ` Linus Torvalds
2023-06-27 21:44   ` Arjan van de Ven
2023-06-27 22:25     ` Linus Torvalds
2023-06-27 22:43       ` Linus Torvalds
2023-06-27 22:50         ` Arjan van de Ven [this message]
2023-06-27 23:02           ` Linus Torvalds
2023-06-27 23:05             ` Arjan van de Ven
2023-06-29  5:29             ` Herbert Xu
2023-06-27 20:52 ` pr-tracker-bot

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