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SubjectRe: perf top for arm64?
Em Tue, Dec 10, 2019 at 05:36:55PM +0100, Jiri Olsa escreveu:
> 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..?

Right, my bad, I'll look into making this just a debug message and then
check in the annotation code when this is really needed to show an
error/popup window :-\

- Arnaldo

> 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;
> > +}
> > +
> >

--

- Arnaldo

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