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authorDavid Daney <ddaney@caviumnetworks.com>2010-02-04 11:31:49 -0800
committerRalf Baechle <ralf@linux-mips.org>2010-02-27 12:53:42 +0100
commit500c2e1fdbcc2b273bd4c695a9b8ac8196f61614 (patch)
treef24c80f609a739beed194fd5c66abf9bc48ce0d6 /arch/mips/Kconfig.debug
parente275ed5ee94b358964a0dae1c8b49f0bff260b60 (diff)
downloadlinux-500c2e1fdbcc2b273bd4c695a9b8ac8196f61614.tar.gz
MIPS: Optimize spinlocks.
The current locking mechanism uses a ll/sc sequence to release a spinlock. This is slower than a wmb() followed by a store to unlock. The branching forward to .subsection 2 on sc failure slows down the contended case. So we get rid of that part too. Since we are now working on naturally aligned u16 values, we can get rid of a masking operation as the LHU already does the right thing. The ANDI are reversed for better scheduling on multi-issue CPUs On a 12 CPU 750MHz Octeon cn5750 this patch improves ipv4 UDP packet forwarding rates from 3.58*10^6 PPS to 3.99*10^6 PPS, or about 11%. Signed-off-by: David Daney <ddaney@caviumnetworks.com> To: linux-mips@linux-mips.org Patchwork: http://patchwork.linux-mips.org/patch/937/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/Kconfig.debug')
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