From mboxrd@z Thu Jan 1 00:00:00 1970 From: ynorov@caviumnetworks.com (Yury Norov) Date: Tue, 11 Apr 2017 01:35:01 +0400 Subject: [RFC PATCH 0/3] arm64: queued spinlocks and rw-locks Message-ID: <1491860104-4103-1-git-send-email-ynorov@caviumnetworks.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org The patch of Jan Glauber enables queued spinlocks on arm64. I rebased it on latest kernel sources, and added a couple of fixes to headers to apply it smoothly. Though, locktourture test shows significant performance degradation in the acquisition of rw-lock for read on qemu: Before After spin_lock-torture: 38957034 37076367 -4.83 rw_lock-torture W: 5369471 18971957 253.33 rw_lock-torture R: 6413179 3668160 -42.80 I'm not much experienced in locking, and so wonder how it's possible that simple switching to generic queued rw-lock causes so significant performance degradation, while in theory it should improve it. Even more, on x86 there are no such problems probably. I also think that patches 1 and 2 are correct and useful, and should be applied anyway. Any comments appreciated. Yury. Jan Glauber (1): arm64/locking: qspinlocks and qrwlocks support Yury Norov (2): kernel/locking: #include in qrwlock.c asm-generic: don't #include in qspinlock_types.h arch/arm64/Kconfig | 2 ++ arch/arm64/include/asm/qrwlock.h | 7 +++++++ arch/arm64/include/asm/qspinlock.h | 20 ++++++++++++++++++++ arch/arm64/include/asm/spinlock.h | 12 ++++++++++++ arch/arm64/include/asm/spinlock_types.h | 14 +++++++++++--- include/asm-generic/qspinlock.h | 1 + include/asm-generic/qspinlock_types.h | 8 -------- kernel/locking/qrwlock.c | 1 + 8 files changed, 54 insertions(+), 11 deletions(-) create mode 100644 arch/arm64/include/asm/qrwlock.h create mode 100644 arch/arm64/include/asm/qspinlock.h -- 2.7.4