linux-kernel - [PATCH] x86, locking: Inline *_unlock_bh & *_unlock

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-next>] [day] [month] [year] [list]

Date:   Thu,  2 Feb 2017 13:36:29 -0500
From:   Waiman Long <longman@...hat.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>
Cc:     linux-kernel@...r.kernel.org, Waiman Long <longman@...hat.com>
Subject: [PATCH] x86, locking: Inline *_unlock_bh & *_unlock_irqrestore

For spinlock and read-write locks, both *_unlock() and *_unlock_irq()
functions are inlined if !PREEMPT. Whereas the *_unlock_bh() and
*unlock_irqrestore() are not inlined as that will increase the size
of the kernel binary.

Given the fact that the PV qspinlock unlock call is a callee-saved
function pointer, the unlock function is essentially a leaf function
if !PREEMPT is true under all circumstances. Inlining it will enable
the compiler to do much better optimization around the the unlock
call sites. Similarly for the read-write locks.

To unleash this additional performance, all these unlock functions
are now inlined for x86-64 kernel where kernel size is usually less
of a concern. For 32-bit kernel, it is assumed that the focus will
be a bit more on kernel size optimization and so those functions are
not inlined.

With 4.9.6 kernel source and gcc 4.8.5-11 compiler, the text size
of the base vmlinux binary increased from 8527918 bytes to 8462235
bytes. That was an increase of 0.78%.

On a 2-socket 24-core 48-thread system, the performance of the AIM7
high_systime workload (1000 users) increased from 209818.43 jobs/min
to 213333.33 jobs/min. That was an increase of 1.68%.

Signed-off-by: Waiman Long <longman@...hat.com>
---
 arch/x86/Kconfig | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 7b6fd68..a0fbed7 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -23,6 +23,12 @@ config X86_64
 	depends on 64BIT
 	# Options that are inherently 64-bit kernel only:
 	select ARCH_HAS_GIGANTIC_PAGE
+	select ARCH_INLINE_READ_UNLOCK_BH		if !PREEMPT
+	select ARCH_INLINE_READ_UNLOCK_IRQRESTORE	if !PREEMPT
+	select ARCH_INLINE_SPIN_UNLOCK_BH		if !PREEMPT
+	select ARCH_INLINE_SPIN_UNLOCK_IRQRESTORE	if !PREEMPT
+	select ARCH_INLINE_WRITE_UNLOCK_BH		if !PREEMPT
+	select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE	if !PREEMPT
 	select ARCH_SUPPORTS_INT128
 	select ARCH_USE_CMPXCHG_LOCKREF
 	select HAVE_ARCH_SOFT_DIRTY
-- 
1.8.3.1