Re: [PATCH 0/1] speeding up cpu_up()
From: Aravind Gopalakrishnan
Date: Sun May 03 2015 - 12:13:47 EST
On 5/1/15 7:42 PM, Aravind Gopalakrishnan wrote:
On 5/1/15 5:47 PM, Borislav Petkov wrote:
On Fri, May 01, 2015 at 02:42:39PM -0700, Len Brown wrote:
On Mon, Apr 20, 2015 at 12:15 AM, Ingo Molnar <mingo@xxxxxxxxxx> wrote:
So instead of playing games with an ancient delay, I'd suggest we
install the 10 msec INIT assertion wait as a platform quirk instead,
and activate it for all CPUs/systems that we think might need it, with
a sufficiently robust and future-proof quirk cutoff condition.
New systems won't have the quirk active and thus won't have to have
this delay configurable either.
Okay, at this time, I think the quirk would apply to:
1. Intel family 5 (original pentium) -- some may actually need the
quirk
2. Intel family F (pentium4) -- mostly b/c I don't want to bother
finding/testing p4
3. All AMD (happy to narrow down, if somebody can speak for AMD)
Aravind and I could probably test on a couple of AMD boxes to narrow
down.
@Aravind, see here:
https://lkml.kernel.org/r/87d69aab88c14d65ae1e7be55050d1b689b59b4b.1429402494.git.len.brown@xxxxxxxxx
You could ask around whether a timeout is needed between the assertion
and deassertion of INIT done by the BSP when booting other cores.
Sure, I'll ask around and try mdelay(0) on some systems as well.
I can gather Fam15h, Fam16h but don't have K8's or older.
Will let you know how it goes.
Update:
Fam15h Model00h-0fh, Fam15hModel60h and Fam16h Model 00h-0fh processors
boot fine with mdelay(0) and BSP brings up all secondary cpus correctly.
I don't have Fam15hModel30h system currently up, but I'll try that too
tomorrow.
I am yet to get feedback from HW folks regarding this though.
Thanks,
-Aravind.
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