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SubjectRe: perf top for arm64?
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On 10/12/2019 16:36, Jiri Olsa wrote:
> 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
>

Hi Jirka,

> 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
>

ok, this is new code. I obviously didn't check the git history...

But, apart from this, there are many other places where get_cpuid() is
called. I wonder what else we're missing out on, and whether we should
still add it.

Thanks,
John

> 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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