From: Adam Wallis <awallis@codeaurora.org> To: Yury Norov <ynorov@caviumnetworks.com>, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: Arnd Bergmann <arnd@arndb.de>, Peter Zijlstra <peterz@infradead.org>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Jan Glauber <jglauber@cavium.com>, Ingo Molnar <mingo@redhat.com>, jason.low2@hp.com Subject: Re: [RFC PATCH 0/3] arm64: queued spinlocks and rw-locks Date: Wed, 12 Apr 2017 13:04:55 -0400 [thread overview] Message-ID: <a4f067df-4c22-5c90-d70a-809903c60296@codeaurora.org> (raw) In-Reply-To: <1491860104-4103-1-git-send-email-ynorov@caviumnetworks.com> On 4/10/2017 5:35 PM, Yury Norov wrote: > 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 > On our 48 core QDF2400 part, I am seeing huge improvements with these patches on the torture tests. The improvements go up even further when I apply Jason Low's MCS Spinlock patch: https://lkml.org/lkml/2016/4/20/725 > 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. > I will be happy to tests these patches more thoroughly after you get some additional comments/feedback. > Jan Glauber (1): > arm64/locking: qspinlocks and qrwlocks support > > Yury Norov (2): > kernel/locking: #include <asm/spinlock.h> in qrwlock.c > asm-generic: don't #include <linux/atomic.h> 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 > Thanks -- Adam Wallis Qualcomm Datacenter Technologies as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
WARNING: multiple messages have this Message-ID (diff)
From: awallis@codeaurora.org (Adam Wallis) To: linux-arm-kernel@lists.infradead.org Subject: [RFC PATCH 0/3] arm64: queued spinlocks and rw-locks Date: Wed, 12 Apr 2017 13:04:55 -0400 [thread overview] Message-ID: <a4f067df-4c22-5c90-d70a-809903c60296@codeaurora.org> (raw) In-Reply-To: <1491860104-4103-1-git-send-email-ynorov@caviumnetworks.com> On 4/10/2017 5:35 PM, Yury Norov wrote: > 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 > On our 48 core QDF2400 part, I am seeing huge improvements with these patches on the torture tests. The improvements go up even further when I apply Jason Low's MCS Spinlock patch: https://lkml.org/lkml/2016/4/20/725 > 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. > I will be happy to tests these patches more thoroughly after you get some additional comments/feedback. > Jan Glauber (1): > arm64/locking: qspinlocks and qrwlocks support > > Yury Norov (2): > kernel/locking: #include <asm/spinlock.h> in qrwlock.c > asm-generic: don't #include <linux/atomic.h> 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 > Thanks -- Adam Wallis Qualcomm Datacenter Technologies as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
next prev parent reply other threads:[~2017-04-12 17:05 UTC|newest] Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-04-10 21:35 [RFC PATCH 0/3] arm64: queued spinlocks and rw-locks Yury Norov 2017-04-10 21:35 ` Yury Norov 2017-04-10 21:35 ` [PATCH 1/3] kernel/locking: #include <asm/spinlock.h> in qrwlock.c Yury Norov 2017-04-10 21:35 ` Yury Norov 2017-04-10 21:35 ` [PATCH 2/3] asm-generic: don't #include <linux/atomic.h> in qspinlock_types.h Yury Norov 2017-04-10 21:35 ` Yury Norov 2017-04-10 21:35 ` [PATCH 3/3] arm64/locking: qspinlocks and qrwlocks support Yury Norov 2017-04-10 21:35 ` Yury Norov 2017-04-13 18:12 ` Peter Zijlstra 2017-04-13 18:12 ` Peter Zijlstra 2017-04-20 18:23 ` Yury Norov 2017-04-20 18:23 ` Yury Norov 2017-04-20 19:00 ` Mark Rutland 2017-04-20 19:00 ` Mark Rutland 2017-04-20 19:05 ` Peter Zijlstra 2017-04-20 19:05 ` Peter Zijlstra 2017-04-26 12:39 ` Yury Norov 2017-04-26 12:39 ` Yury Norov 2017-04-28 15:44 ` Will Deacon 2017-04-28 15:44 ` Will Deacon 2017-04-12 17:04 ` Adam Wallis [this message] 2017-04-12 17:04 ` [RFC PATCH 0/3] arm64: queued spinlocks and rw-locks Adam Wallis 2017-04-13 10:33 ` Yury Norov 2017-04-13 10:33 ` Yury Norov 2017-04-28 15:37 ` Will Deacon 2017-04-28 15:37 ` Will Deacon 2017-04-24 13:36 ` Will Deacon 2017-04-24 13:36 ` Will Deacon
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