From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Balbir Singh <bsingharora@gmail.com>,
paulus@samba.org, mpe@ellerman.id.au
Cc: linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] powerpc/mm: Use jump label to speed up radix_enabled check
Date: Wed, 27 Apr 2016 12:30:30 +0530 [thread overview]
Message-ID: <87mvofedtd.fsf@skywalker.in.ibm.com> (raw)
In-Reply-To: <1461721589.3586.0.camel@kernel.crashing.org>
Benjamin Herrenschmidt <benh@kernel.crashing.org> writes:
> On Wed, 2016-04-27 at 11:00 +1000, Balbir Singh wrote:
>> Just basic testing across CPUs with various mm features=C2=A0
>> enabled/disabled. Just for sanity
>
> I still don't think it's worth scattering the change. Either the jump
> label works or it doesn't ... The only problem is make sure we identify
> all the pre-boot ones but that's about it.
>
There are two ways to do this. One is to follow the approach listed
below done by Kevin, which is to do the jump_label_init early during boot a=
nd
switch both cpu and mmu feature check to plain jump label.
http://mid.gmane.org/1440415228-8006-1-git-send-email-haokexin@gmail.com
I already found one use case of cpu_has_feature before that
jump_label_init. In this approach we need to carefully audit all the
cpu/mmu_has_feature calls to make sure they don't get called before
jump_label_init. A missed conversion mean we miss a cpu/mmu feature
check.
Other option is to follow the patch I posted above, with the simple
change of renaming mmu_feature_enabled to mmu_has_feature. So we can
use it in early boot without really worrying about when we init jump
label.
What do you suggest we follow ?
-aneesh
next prev parent reply other threads:[~2016-04-27 7:00 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-26 16:24 [PATCH] powerpc/mm: Use jump label to speed up radix_enabled check Aneesh Kumar K.V
2016-04-26 21:05 ` Benjamin Herrenschmidt
2016-04-26 22:16 ` Balbir Singh
2016-04-26 23:05 ` Benjamin Herrenschmidt
2016-04-27 1:00 ` Balbir Singh
2016-04-27 1:46 ` Benjamin Herrenschmidt
2016-04-27 7:00 ` Aneesh Kumar K.V [this message]
2016-04-27 9:30 ` Aneesh Kumar K.V
2016-06-09 4:12 ` Benjamin Herrenschmidt
2016-06-09 6:00 ` Aneesh Kumar K.V
2016-06-09 15:58 ` Aneesh Kumar K.V
2016-06-10 4:16 ` Michael Ellerman
2016-06-10 5:46 ` Benjamin Herrenschmidt
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