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Fri, 28 Aug 2020 15:55:18 +0800 From: "Song Bao Hua (Barry Song)" To: Jean-Philippe Brucker Subject: RE: [PATCH] iommu/arm-smmu-v3: add tracepoints for cmdq_issue_cmdlist Thread-Topic: [PATCH] iommu/arm-smmu-v3: add tracepoints for cmdq_issue_cmdlist Thread-Index: AQHWfFWUhbwMm9rWP0CSbrIWukW28qlMnmaAgACI9/A= Date: Fri, 28 Aug 2020 07:55:18 +0000 Message-ID: References: <20200827093351.15244-1-song.bao.hua@hisilicon.com> <20200828074107.GB3825485@myrica> In-Reply-To: <20200828074107.GB3825485@myrica> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.126.200.243] MIME-Version: 1.0 X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200828_035602_354355_6AFB9A29 X-CRM114-Status: GOOD ( 26.65 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "will@kernel.org" , "iommu@lists.linux-foundation.org" , "robin.murphy@arm.com" , Linuxarm , "linux-arm-kernel@lists.infradead.org" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org > -----Original Message----- > From: Jean-Philippe Brucker [mailto:jean-philippe@linaro.org] > Sent: Friday, August 28, 2020 7:41 PM > To: Song Bao Hua (Barry Song) > Cc: iommu@lists.linux-foundation.org; linux-arm-kernel@lists.infradead.org; > robin.murphy@arm.com; will@kernel.org; Linuxarm > Subject: Re: [PATCH] iommu/arm-smmu-v3: add tracepoints for > cmdq_issue_cmdlist > > Hi, > > On Thu, Aug 27, 2020 at 09:33:51PM +1200, Barry Song wrote: > > cmdq_issue_cmdlist() is the hotspot that uses a lot of time. This > > patch adds tracepoints for it to help debug. > > > > Signed-off-by: Barry Song > > --- > > * can furthermore develop an eBPF program to benchmark using this > > trace > > Have you tried using kprobe and kretprobe instead of tracepoints? > Any noticeable performance drop? Yes. Pls read this email. kprobe overhead and OPTPROBES implementation on ARM64 https://www.spinics.net/lists/arm-kernel/msg828788.html > > Thanks, > Jean > > > > > cmdlistlat.c: > > #include > > > > BPF_HASH(start, u32); > > BPF_HISTOGRAM(dist); > > > > TRACEPOINT_PROBE(arm_smmu_v3, issue_cmdlist_entry) { > > u32 pid; > > u64 ts, *val; > > > > pid = bpf_get_current_pid_tgid(); > > ts = bpf_ktime_get_ns(); > > start.update(&pid, &ts); > > return 0; > > } > > > > TRACEPOINT_PROBE(arm_smmu_v3, issue_cmdlist_exit) { > > u32 pid; > > u64 *tsp, delta; > > > > pid = bpf_get_current_pid_tgid(); > > tsp = start.lookup(&pid); > > > > if (tsp != 0) { > > delta = bpf_ktime_get_ns() - *tsp; > > dist.increment(bpf_log2l(delta)); > > start.delete(&pid); > > } > > > > return 0; > > } > > > > cmdlistlat.py: > > #!/usr/bin/python3 > > # > > from __future__ import print_function > > from bcc import BPF > > from ctypes import c_ushort, c_int, c_ulonglong from time import sleep > > from sys import argv > > > > def usage(): > > print("USAGE: %s [interval [count]]" % argv[0]) > > exit() > > > > # arguments > > interval = 5 > > count = -1 > > if len(argv) > 1: > > try: > > interval = int(argv[1]) > > if interval == 0: > > raise > > if len(argv) > 2: > > count = int(argv[2]) > > except: # also catches -h, --help > > usage() > > > > # load BPF program > > b = BPF(src_file = "cmdlistlat.c") > > > > # header > > print("Tracing... Hit Ctrl-C to end.") > > > > # output > > loop = 0 > > do_exit = 0 > > while (1): > > if count > 0: > > loop += 1 > > if loop > count: > > exit() > > try: > > sleep(interval) > > except KeyboardInterrupt: > > pass; do_exit = 1 > > > > print() > > b["dist"].print_log2_hist("nsecs") > > b["dist"].clear() > > if do_exit: > > exit() > > > > > > drivers/iommu/arm/arm-smmu-v3/Makefile | 1 + > > .../iommu/arm/arm-smmu-v3/arm-smmu-v3-trace.h | 48 > +++++++++++++++++++ > > drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 8 ++++ > > 3 files changed, 57 insertions(+) > > create mode 100644 > drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-trace.h > > > > diff --git a/drivers/iommu/arm/arm-smmu-v3/Makefile > > b/drivers/iommu/arm/arm-smmu-v3/Makefile > > index 569e24e9f162..dba1087f91f3 100644 > > --- a/drivers/iommu/arm/arm-smmu-v3/Makefile > > +++ b/drivers/iommu/arm/arm-smmu-v3/Makefile > > @@ -1,2 +1,3 @@ > > # SPDX-License-Identifier: GPL-2.0 > > +ccflags-y += -I$(src) # needed for trace events > > obj-$(CONFIG_ARM_SMMU_V3) += arm-smmu-v3.o diff --git > > a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-trace.h > > b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-trace.h > > new file mode 100644 > > index 000000000000..29ab96706124 > > --- /dev/null > > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-trace.h > > @@ -0,0 +1,48 @@ > > +/* SPDX-License-Identifier: GPL-2.0-only */ > > +/* > > + * Copyright (C) 2020 Hisilicon Limited. > > + */ > > + > > +#undef TRACE_SYSTEM > > +#define TRACE_SYSTEM arm_smmu_v3 > > + > > +#if !defined(_ARM_SMMU_V3_TRACE_H) || > > +defined(TRACE_HEADER_MULTI_READ) #define _ARM_SMMU_V3_TRACE_H > > + > > +#include > > + > > +struct device; > > + > > +DECLARE_EVENT_CLASS(issue_cmdlist_class, > > + TP_PROTO(struct device *dev, int n, bool sync), > > + TP_ARGS(dev, n, sync), > > + > > + TP_STRUCT__entry( > > + __string(device, dev_name(dev)) > > + __field(int, n) > > + __field(bool, sync) > > + ), > > + TP_fast_assign( > > + __assign_str(device, dev_name(dev)); > > + __entry->n = n; > > + __entry->sync = sync; > > + ), > > + TP_printk("%s cmd number=%d sync=%d", > > + __get_str(device), __entry->n, __entry->sync) ); > > + > > +#define DEFINE_ISSUE_CMDLIST_EVENT(name) \ > > +DEFINE_EVENT(issue_cmdlist_class, name, \ > > + TP_PROTO(struct device *dev, int n, bool sync), \ > > + TP_ARGS(dev, n, sync)) > > + > > +DEFINE_ISSUE_CMDLIST_EVENT(issue_cmdlist_entry); > > +DEFINE_ISSUE_CMDLIST_EVENT(issue_cmdlist_exit); > > + > > +#endif /* _ARM_SMMU_V3_TRACE_H */ > > + > > +#undef TRACE_INCLUDE_PATH > > +#undef TRACE_INCLUDE_FILE > > +#define TRACE_INCLUDE_PATH . > > +#define TRACE_INCLUDE_FILE arm-smmu-v3-trace #include > > + > > diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > > b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > > index 7332251dd8cd..e2d7d5f1d234 100644 > > --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > > @@ -33,6 +33,8 @@ > > > > #include > > > > +#include "arm-smmu-v3-trace.h" > > + > > /* MMIO registers */ > > #define ARM_SMMU_IDR0 0x0 > > #define IDR0_ST_LVL GENMASK(28, 27) > > @@ -1389,6 +1391,8 @@ static int arm_smmu_cmdq_issue_cmdlist(struct > arm_smmu_device *smmu, > > }, head = llq; > > int ret = 0; > > > > + trace_issue_cmdlist_entry(smmu->dev, n, sync); > > + > > /* 1. Allocate some space in the queue */ > > local_irq_save(flags); > > llq.val = READ_ONCE(cmdq->q.llq.val); @@ -1493,6 +1497,7 @@ static > > int arm_smmu_cmdq_issue_cmdlist(struct arm_smmu_device *smmu, > > } > > > > local_irq_restore(flags); > > + trace_issue_cmdlist_exit(smmu->dev, n, sync); > > return ret; > > } > > > > @@ -4166,6 +4171,9 @@ static struct platform_driver arm_smmu_driver = > > { }; module_platform_driver(arm_smmu_driver); > > > > +#define CREATE_TRACE_POINTS > > +#include "arm-smmu-v3-trace.h" > > + > > MODULE_DESCRIPTION("IOMMU API for ARM architected SMMUv3 > > implementations"); MODULE_AUTHOR("Will Deacon "); > > MODULE_ALIAS("platform:arm-smmu-v3"); > > -- > > 2.27.0 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel