linux-kernel - Re: [PATCH] x86: skip delays during SMP initialization similar to Xen

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAJvTdKn9scxP52FycyFaROdhhwbn-1V08SvMi2RJkykD79sDKA@mail.gmail.com>
Date:	Thu, 14 May 2015 03:18:42 -0400
From:	Len Brown <lenb@...nel.org>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Jan H. Schönherr <jschoenh@...zon.de>,
	Thomas Gleixner <tglx@...utronix.de>, X86 ML <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Anthony Liguori <aliguori@...zon.com>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Tim Deegan <tim@....org>,
	Gang Wei <gang.wei@...el.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH] x86: skip delays during SMP initialization similar to Xen

On Thu, May 14, 2015 at 2:36 AM, Len Brown <lenb@...nel.org> wrote:

>> [    2.737884] x86: Booted up 4 nodes, 120 CPUs

> For the record, the same (bare metal) box running latest tip boots
> 10ms/processor quicker

> [    1.553658] x86: Booted up 4 nodes, 120 CPUs

> BTW. this time can be reduced by 7% (113 ms) by deleting announce_cpu():
>
> [    1.445815] x86: Booted up 4 nodes, 120 CPUs

I see that the x2apic optimization has been reverted from TIP.
So just for grins, I booted the same box with all the udelays in
smpboot.c removed,
and it speed up boot by only 12ms (0.8%) total:

[    1.432946] x86: Booted up 4 nodes, 120 CPUs

cheers,
-Len Brown, Intel Open Source Technology Center
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/