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SubjectRe: perf top for arm64?
On Tue, Dec 10, 2019 at 04:13:49PM +0000, John Garry wrote:
> Hi all,
>
> I find to my surprise that "perf top" does not work for arm64:
>
> root@ubuntu:/home/john/linux# tools/perf/perf top
> Couldn't read the cpuid for this machine: No such file or directory

there was recent change that check on cpuid and quits:
608127f73779 perf top: Initialize perf_env->cpuid, needed by the per arch annotation init routine

Arnaldo,
maybe this should be just a warning/info, because it seems to be related
to annotations only..?

get_cpuid is defined only for s390/x86/powerpc, so I guess it won't work
on the rest as well

jirka

>
> That's v5.5-rc1 release.
>
> It seems that we are just missing an arm64 version of get_cpuid() - with the
> patch below, I now get as hoped:
>
> PerfTop: 32857 irqs/sec kernel:85.0% exact: 0.0% lost: 0/0 drop: 0/0
> [4000Hz cycles], (all, 64 CPUs)
> -------------------------------------------------------------------------------
>
> 8.99% [kernel] [k] arm_smmu_cmdq_issue_cmdlist
> 5.80% [kernel] [k] __softirqentry_text_start
> 4.49% [kernel] [k] _raw_spin_unlock_irqrestore
> 3.48% [kernel] [k] el0_svc_common.constprop.2
> 3.37% [kernel] [k] _raw_write_lock_irqsave
> 3.28% [kernel] [k] __local_bh_enable_ip
> 3.05% [kernel] [k] __blk_complete_request
> 2.07% [kernel] [k] queued_spin_lock_slowpath
> 1.93% [vdso] [.] 0x0000000000000484
>
>
> Was this just missed? Or is there a good reason to omit?
>
> Thanks,
> John
>
> --->8---
>
> Subject: [PATCH] perf: Add perf top support for arm64
>
> Copied from get_cpuid_str() essentially...
>
> Signed-off-by: John Garry <john.garry@huawei.com>
>
> diff --git a/tools/perf/arch/arm64/util/header.c
> b/tools/perf/arch/arm64/util/header.c
> index a32e4b72a98f..ecd1f86e29cc 100644
> --- a/tools/perf/arch/arm64/util/header.c
> +++ b/tools/perf/arch/arm64/util/header.c
> @@ -1,10 +1,12 @@
> #include <stdio.h>
> #include <stdlib.h>
> #include <perf/cpumap.h>
> +#include <util/cpumap.h>
> #include <internal/cpumap.h>
> #include <api/fs/fs.h>
> #include "debug.h"
> #include "header.h"
> +#include <errno.h>
>
> #define MIDR "/regs/identification/midr_el1"
> #define MIDR_SIZE 19
> @@ -12,6 +14,59 @@
> #define MIDR_VARIANT_SHIFT 20
> #define MIDR_VARIANT_MASK (0xf << MIDR_VARIANT_SHIFT)
>
> +int
> +get_cpuid(char *buffer, size_t sz)
> +{
> + char *buf = NULL;
> + char path[PATH_MAX];
> + const char *sysfs = sysfs__mountpoint();
> + int cpu;
> + u64 midr = 0;
> + FILE *file;
> +
> + if (!sysfs)
> + return EINVAL;
> +
> + buf = malloc(MIDR_SIZE);
> + if (!buf)
> + return EINVAL;
> +
> + /* read midr from list of cpus mapped to this pmu */
> + for (cpu = 0; cpu < cpu__max_present_cpu(); cpu++) {
> + scnprintf(path, sz, "%s/devices/system/cpu/cpu%d"MIDR,
> + sysfs, cpu);
> +
> + file = fopen(path, "r");
> + if (!file) {
> + pr_debug("fopen failed for file %s\n", path);
> + continue;
> + }
> +
> + if (!fgets(buf, MIDR_SIZE, file)) {
> + fclose(file);
> + continue;
> + }
> + fclose(file);
> +
> + /* Ignore/clear Variant[23:20] and
> + * Revision[3:0] of MIDR
> + */
> + midr = strtoul(buf, NULL, 16);
> + midr &= (~(MIDR_VARIANT_MASK | MIDR_REVISION_MASK));
> + scnprintf(buffer, MIDR_SIZE, "0x%016lx", midr);
> + /* got midr break loop */
> + break;
> + }
> +
> + if (!midr) {
> + pr_err("failed to get cpuid string\n");
> + free(buf);
> + return EINVAL;
> + }
> + return 0;
> +}
> +
>

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