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Fri, 15 Sep 2023 02:08:14 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFhPuE0vVQrZ5yNVV2/CRzGgjDbJWsGNubkMQ9VFFqioUnDUIXm3xLcqgaJvFTYyDGsececmw== X-Received: by 2002:a05:6830:1bd6:b0:6bd:db8:db with SMTP id v22-20020a0568301bd600b006bd0db800dbmr943720ota.32.1694768893783; Fri, 15 Sep 2023 02:08:13 -0700 (PDT) Received: from redhat.com ([2804:1b3:a803:4ff9:7c29:fe41:6aa7:43df]) by smtp.gmail.com with ESMTPSA id 6-20020a4a1406000000b00562f3936c01sm1538286ood.45.2023.09.15.02.08.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 15 Sep 2023 02:08:13 -0700 (PDT) Date: Fri, 15 Sep 2023 06:08:04 -0300 From: Leonardo Bras To: Guo Ren Cc: paul.walmsley@sifive.com, anup@brainfault.org, peterz@infradead.org, mingo@redhat.com, will@kernel.org, palmer@rivosinc.com, longman@redhat.com, boqun.feng@gmail.com, tglx@linutronix.de, paulmck@kernel.org, rostedt@goodmis.org, rdunlap@infradead.org, catalin.marinas@arm.com, conor.dooley@microchip.com, xiaoguang.xing@sophgo.com, bjorn@rivosinc.com, alexghiti@rivosinc.com, keescook@chromium.org, greentime.hu@sifive.com, ajones@ventanamicro.com, jszhang@kernel.org, wefu@redhat.com, wuwei2016@iscas.ac.cn, linux-arch@vger.kernel.org, linux-riscv@lists.infradead.org, linux-doc@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-csky@vger.kernel.org, Guo Ren Subject: Re: [PATCH V11 05/17] riscv: qspinlock: Add basic queued_spinlock support Message-ID: References: <20230910082911.3378782-1-guoren@kernel.org> <20230910082911.3378782-6-guoren@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-csky@vger.kernel.org On Fri, Sep 15, 2023 at 10:10:25AM +0800, Guo Ren wrote: > On Thu, Sep 14, 2023 at 5:43 PM Leonardo Bras wrote: > > > > On Thu, Sep 14, 2023 at 12:46:56PM +0800, Guo Ren wrote: > > > On Thu, Sep 14, 2023 at 4:29 AM Leonardo Bras wrote: > > > > > > > > On Sun, Sep 10, 2023 at 04:28:59AM -0400, guoren@kernel.org wrote: > > > > > From: Guo Ren > > > > > > > > > > The requirements of qspinlock have been documented by commit: > > > > > a8ad07e5240c ("asm-generic: qspinlock: Indicate the use of mixed-size > > > > > atomics"). > > > > > > > > > > Although RISC-V ISA gives out a weaker forward guarantee LR/SC, which > > > > > doesn't satisfy the requirements of qspinlock above, it won't prevent > > > > > some riscv vendors from implementing a strong fwd guarantee LR/SC in > > > > > microarchitecture to match xchg_tail requirement. T-HEAD C9xx processor > > > > > is the one. > > > > > > > > > > We've tested the patch on SOPHGO sg2042 & th1520 and passed the stress > > > > > test on Fedora & Ubuntu & OpenEuler ... Here is the performance > > > > > comparison between qspinlock and ticket_lock on sg2042 (64 cores): > > > > > > > > > > sysbench test=threads threads=32 yields=100 lock=8 (+13.8%): > > > > > queued_spinlock 0.5109/0.00 > > > > > ticket_spinlock 0.5814/0.00 > > > > > > > > > > perf futex/hash (+6.7%): > > > > > queued_spinlock 1444393 operations/sec (+- 0.09%) > > > > > ticket_spinlock 1353215 operations/sec (+- 0.15%) > > > > > > > > > > perf futex/wake-parallel (+8.6%): > > > > > queued_spinlock (waking 1/64 threads) in 0.0253 ms (+-2.90%) > > > > > ticket_spinlock (waking 1/64 threads) in 0.0275 ms (+-3.12%) > > > > > > > > > > perf futex/requeue (+4.2%): > > > > > queued_spinlock Requeued 64 of 64 threads in 0.0785 ms (+-0.55%) > > > > > ticket_spinlock Requeued 64 of 64 threads in 0.0818 ms (+-4.12%) > > > > > > > > > > System Benchmarks (+6.4%) > > > > > queued_spinlock: > > > > > System Benchmarks Index Values BASELINE RESULT INDEX > > > > > Dhrystone 2 using register variables 116700.0 628613745.4 53865.8 > > > > > Double-Precision Whetstone 55.0 182422.8 33167.8 > > > > > Execl Throughput 43.0 13116.6 3050.4 > > > > > File Copy 1024 bufsize 2000 maxblocks 3960.0 7762306.2 19601.8 > > > > > File Copy 256 bufsize 500 maxblocks 1655.0 3417556.8 20649.9 > > > > > File Copy 4096 bufsize 8000 maxblocks 5800.0 7427995.7 12806.9 > > > > > Pipe Throughput 12440.0 23058600.5 18535.9 > > > > > Pipe-based Context Switching 4000.0 2835617.7 7089.0 > > > > > Process Creation 126.0 12537.3 995.0 > > > > > Shell Scripts (1 concurrent) 42.4 57057.4 13456.9 > > > > > Shell Scripts (8 concurrent) 6.0 7367.1 12278.5 > > > > > System Call Overhead 15000.0 33308301.3 22205.5 > > > > > ======== > > > > > System Benchmarks Index Score 12426.1 > > > > > > > > > > ticket_spinlock: > > > > > System Benchmarks Index Values BASELINE RESULT INDEX > > > > > Dhrystone 2 using register variables 116700.0 626541701.9 53688.2 > > > > > Double-Precision Whetstone 55.0 181921.0 33076.5 > > > > > Execl Throughput 43.0 12625.1 2936.1 > > > > > File Copy 1024 bufsize 2000 maxblocks 3960.0 6553792.9 16550.0 > > > > > File Copy 256 bufsize 500 maxblocks 1655.0 3189231.6 19270.3 > > > > > File Copy 4096 bufsize 8000 maxblocks 5800.0 7221277.0 12450.5 > > > > > Pipe Throughput 12440.0 20594018.7 16554.7 > > > > > Pipe-based Context Switching 4000.0 2571117.7 6427.8 > > > > > Process Creation 126.0 10798.4 857.0 > > > > > Shell Scripts (1 concurrent) 42.4 57227.5 13497.1 > > > > > Shell Scripts (8 concurrent) 6.0 7329.2 12215.3 > > > > > System Call Overhead 15000.0 30766778.4 20511.2 > > > > > ======== > > > > > System Benchmarks Index Score 11670.7 > > > > > > > > > > The qspinlock has a significant improvement on SOPHGO SG2042 64 > > > > > cores platform than the ticket_lock. > > > > > > > > > > Signed-off-by: Guo Ren > > > > > Signed-off-by: Guo Ren > > > > > --- > > > > > arch/riscv/Kconfig | 16 ++++++++++++++++ > > > > > arch/riscv/include/asm/Kbuild | 3 ++- > > > > > arch/riscv/include/asm/spinlock.h | 17 +++++++++++++++++ > > > > > 3 files changed, 35 insertions(+), 1 deletion(-) > > > > > create mode 100644 arch/riscv/include/asm/spinlock.h > > > > > > > > > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > > > > > index 2c346fe169c1..7f39bfc75744 100644 > > > > > --- a/arch/riscv/Kconfig > > > > > +++ b/arch/riscv/Kconfig > > > > > @@ -471,6 +471,22 @@ config NODES_SHIFT > > > > > Specify the maximum number of NUMA Nodes available on the target > > > > > system. Increases memory reserved to accommodate various tables. > > > > > > > > > > +choice > > > > > + prompt "RISC-V spinlock type" > > > > > + default RISCV_TICKET_SPINLOCKS > > > > > + > > > > > +config RISCV_TICKET_SPINLOCKS > > > > > + bool "Using ticket spinlock" > > > > > + > > > > > +config RISCV_QUEUED_SPINLOCKS > > > > > + bool "Using queued spinlock" > > > > > + depends on SMP && MMU > > > > > + select ARCH_USE_QUEUED_SPINLOCKS > > > > > + help > > > > > + Make sure your micro arch LL/SC has a strong forward progress guarantee. > > > > > + Otherwise, stay at ticket-lock. > > > > > +endchoice > > > > > + > > > > > config RISCV_ALTERNATIVE > > > > > bool > > > > > depends on !XIP_KERNEL > > > > > diff --git a/arch/riscv/include/asm/Kbuild b/arch/riscv/include/asm/Kbuild > > > > > index 504f8b7e72d4..a0dc85e4a754 100644 > > > > > --- a/arch/riscv/include/asm/Kbuild > > > > > +++ b/arch/riscv/include/asm/Kbuild > > > > > @@ -2,10 +2,11 @@ > > > > > generic-y += early_ioremap.h > > > > > generic-y += flat.h > > > > > generic-y += kvm_para.h > > > > > +generic-y += mcs_spinlock.h > > > > > generic-y += parport.h > > > > > -generic-y += spinlock.h > > > > > > > > IIUC here you take the asm-generic/spinlock.h (which defines arch_spin_*()) > > > > and include the asm-generic headers of mcs_spinlock and qspinlock. > > > > > > > > In this case, the qspinlock.h will provide the arch_spin_*() interfaces, > > > > which seems the oposite of the above description (ticket spinlocks being > > > > the standard). > > > > > > > > Shouldn't ticket-spinlock.h also get included here? > > > > (Also, I am probably missing something, as I dont' see the use of > > > > mcs_spinlock here.) > > > No, because asm-generic/spinlock.h: > > > ... > > > #include > > > ... > > > > > > > But aren't you removing asm-generic/spinlock.h below ? > > -generic-y += spinlock.h > Yes, current is: > > arch/riscv/include/asm/spinlock.h -> include/asm-generic/spinlock.h -> > include/asm-generic/ticket_spinlock.h I did a little reading on how generic-y works (which I was unaware): "If an architecture uses a verbatim copy of a header from include/asm-generic then this is listed in the file arch/$(SRCARCH)/include/asm/Kbuild [...] During the prepare phase of the build a wrapper include file is generated in the directory [...]" Oh, so you are removing the asm-generic/spinlock.h because it's link was replaced by a new asm/spinlock.h. You add qspinlock.h to generic-y because it's new in riscv, and add mcs_spinlock.h because it's needed by qspinlock.h. Ok, it makes sense now. Sorry about this noise. I was unaware of how generic-y worked, and (wrongly) assumed it was about including headers automatically in the build. > > +#ifdef CONFIG_QUEUED_SPINLOCKS > +#include > +#include > +#else > +#include > +#endif > > So, you want me: > +#ifdef CONFIG_QUEUED_SPINLOCKS > +#include > +#else > +#include > +#endif > > +#include > > Right? No, I didn't mean that. I was just worried about the arch_spin_*() interfaces, but they should be fine. BTW, according to kernel doc on generic-y, shouldn't be a better idea to add 'ticket_spinlock.h' to generic-y, and include above as asm/ticket_spinlock.h? Or is generic-y reserved only for stuff which is indirectly included by other headers? Thanks! Leo > > > > > > > > > > > > generic-y += spinlock_types.h > > > > > generic-y += qrwlock.h > > > > > generic-y += qrwlock_types.h > > > > > +generic-y += qspinlock.h > > > > > generic-y += user.h > > > > > generic-y += vmlinux.lds.h > > > > > diff --git a/arch/riscv/include/asm/spinlock.h b/arch/riscv/include/asm/spinlock.h > > > > > new file mode 100644 > > > > > index 000000000000..c644a92d4548 > > > > > --- /dev/null > > > > > +++ b/arch/riscv/include/asm/spinlock.h > > > > > @@ -0,0 +1,17 @@ > > > > > +/* SPDX-License-Identifier: GPL-2.0 */ > > > > > + > > > > > +#ifndef __ASM_RISCV_SPINLOCK_H > > > > > +#define __ASM_RISCV_SPINLOCK_H > > > > > + > > > > > +#ifdef CONFIG_QUEUED_SPINLOCKS > > > > > +#define _Q_PENDING_LOOPS (1 << 9) > > > > > +#endif > > > > > > > > Any reason the above define couldn't be merged on the ifdef below? > > > Easy for the next patch to modify. See Waiman's comment: > > > > > > https://lore.kernel.org/linux-riscv/4cc7113a-0e4e-763a-cba2-7963bcd26c7a@redhat.com/ > > > > > > > diff --git a/arch/riscv/include/asm/spinlock.h b/arch/riscv/include/asm/spinlock.h > > > > index c644a92d4548..9eb3ad31e564 100644 > > > > --- a/arch/riscv/include/asm/spinlock.h > > > > +++ b/arch/riscv/include/asm/spinlock.h > > > > @@ -7,11 +7,94 @@ > > > > #define _Q_PENDING_LOOPS (1 << 9) > > > > #endif > > > > > > > > > > I see why you separated the _Q_PENDING_LOOPS out. > > > > > > > I see, should be fine then. > > > > Thanks! > > Leo > > > > > > > > > > > > > > + > > > > > +#ifdef CONFIG_QUEUED_SPINLOCKS > > > > > +#include > > > > > +#include > > > > > +#else > > > > > +#include > > > > > +#endif > > > > > + > > > > > +#endif /* __ASM_RISCV_SPINLOCK_H */ > > > > > -- > > > > > 2.36.1 > > > > > > > > > > > > > Thanks! > > > > Leo > > > > > > > > > > > > > -- > > > Best Regards > > > Guo Ren > > > > > > > > -- > Best Regards > Guo Ren >