linux-kernel - [PATCH v2 0/3] Optimize CONFIG_DEBUG

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Message-Id: <1453884618-33852-1-git-send-email-borntraeger@de.ibm.com>
Date:	Wed, 27 Jan 2016 09:50:15 +0100
From:	Christian Borntraeger <borntraeger@...ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	akpm@...ux-foundation.org, linux-mm@...ck.org,
	linux-arch@...r.kernel.org, linux-s390@...r.kernel.org,
	x86@...nel.org, linuxppc-dev@...ts.ozlabs.org, davem@...emloft.net,
	Joonsoo Kim <iamjoonsoo.kim@....com>, davej@...emonkey.org.uk,
	Christian Borntraeger <borntraeger@...ibm.com>
Subject: [PATCH v2 0/3] Optimize CONFIG_DEBUG_PAGEALLOC

As CONFIG_DEBUG_PAGEALLOC can be enabled/disabled via kernel
parameters we can optimize some cases by checking the enablement
state.

I have done s390 and x86 as examples.
s390 should be ok, I tested several combinations, x86 seems to
work as well, but I have some concerns about the 1GB pages.
The previous code did not bother at all with CONFIG_DEBUG_PAGEALLOC
and I do not fully understand why.

Power can probably do the same, Michael/Ben?
I am not sure about sparc. Sparc seems to allocate the TSB buffer
really early. David?

V1->V2:
- replace DEBUG_PAGEALLOC(disabled/enabled) with DEBUG_PAGEALLOC
  dump_stack for s390/x86
- add /* CONFIG_DEBUG_PAGEALLOC */ to else and endif

Christian Borntraeger (3):
  mm: provide debug_pagealloc_enabled() without CONFIG_DEBUG_PAGEALLOC
  x86: query dynamic DEBUG_PAGEALLOC setting
  s390: query dynamic DEBUG_PAGEALLOC setting

 arch/s390/kernel/dumpstack.c |  8 ++++----
 arch/s390/mm/vmem.c          | 10 ++++------
 arch/x86/kernel/dumpstack.c  |  5 ++---
 arch/x86/mm/init.c           |  7 ++++---
 arch/x86/mm/pageattr.c       | 14 ++++----------
 include/linux/mm.h           |  9 +++++++--
 6 files changed, 25 insertions(+), 28 deletions(-)

-- 
2.3.0