From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Peter Zijlstra <peterz@infradead.org>,
Kyle Huey <khuey@kylehuey.com>, Andy Lutomirski <luto@kernel.org>
Subject: [patch 0/3] x86/process: Optimize __switch_to_extra()
Date: Thu, 15 Dec 2016 16:44:01 -0000 [thread overview]
Message-ID: <20161215162648.061449202@linutronix.de> (raw)
GCC generates lousy code in __switch_to_extra(). Aside of that some of the
operations there are implemented suboptimal.
This series, inspired by a patch from Kyle, helps the compiler to be less
stupid by explicitely giving the hints to optimize and replaces the open
coded bit toggle mechanisms with proper helper functions.
The resulting change in text size:
64bit 32bit
Before: 3726 9388
After: 3646 9324
Delta: 80 152
The number of conditional jumps is also reduced:
64bit 32bit
Before: 8 13
After: 5 10
Thanks,
tglx
---
include/asm/processor.h | 12 ++++++++
include/asm/tlbflush.h | 10 ++++++
kernel/process.c | 70 +++++++++++++++++++-----------------------------
3 files changed, 51 insertions(+), 41 deletions(-)
next reply other threads:[~2016-12-15 16:47 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-15 16:44 Thomas Gleixner [this message]
2016-12-15 16:44 ` [patch 2/3] x86/process: Optimize TIF_BLOCKSTEP switch Thomas Gleixner
2016-12-15 17:28 ` Andy Lutomirski
2016-12-16 8:47 ` Thomas Gleixner
2016-12-16 19:22 ` Andy Lutomirski
2016-12-15 16:44 ` [patch 1/3] x86/process: Optimize TIF checks in switch_to_extra() Thomas Gleixner
2016-12-15 17:20 ` Peter Zijlstra
2016-12-15 17:26 ` Thomas Gleixner
2016-12-15 17:33 ` Peter Zijlstra
2016-12-15 17:24 ` Andy Lutomirski
2016-12-15 16:44 ` [patch 3/3] x86/process: Optimize TIF_NOTSC switch Thomas Gleixner
2016-12-15 17:31 ` Andy Lutomirski
2016-12-16 8:50 ` Thomas Gleixner
2016-12-16 18:34 ` Andy Lutomirski
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