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 <song.bao....@hisilicon.com>
---
* can furthermore develop an eBPF program to benchmark using this trace
cmdlistlat.c:
#include <uapi/linux/ptrace.h>
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 <linux/tracepoint.h>
+
+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 <trace/define_trace.h>
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 <linux/amba/bus.h>
+#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 <w...@kernel.org>");
MODULE_ALIAS("platform:arm-smmu-v3");
--
2.27.0
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