| Message ID | 20210711104105.505728-11-leo.yan@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | perf: Refine barriers for AUX ring buffer | expand |
On 11/07/21 1:41 pm, Leo Yan wrote: > It's useful to know that the kernel is running in 32-bit or 64-bit > mode. E.g. We can decide if perf tool is running in compat mode > from this info. > > This patch adds a global variable "kernel_is_64_bit", it's initialized > when a session setups environment, its value is decided by checking the > architecture string. > > Signed-off-by: Leo Yan <leo.yan@linaro.org> > --- > tools/perf/util/env.c | 17 ++++++++++++++++- > tools/perf/util/env.h | 1 + > 2 files changed, 17 insertions(+), 1 deletion(-) > > diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c > index ebc5e9ad35db..345635a2e842 100644 > --- a/tools/perf/util/env.c > +++ b/tools/perf/util/env.c > @@ -11,6 +11,7 @@ > #include <stdlib.h> > #include <string.h> > > +int kernel_is_64_bit; > struct perf_env perf_env; > > #ifdef HAVE_LIBBPF_SUPPORT > @@ -172,6 +173,19 @@ static void perf_env__purge_bpf(struct perf_env *env __maybe_unused) > } > #endif // HAVE_LIBBPF_SUPPORT > > +static void perf_env__init_kernel_mode(struct perf_env *env) > +{ > + const char *arch = perf_env__raw_arch(env); > + > + if (!strncmp(arch, "x86_64", 6) || !strncmp(arch, "aarch64", 7) || > + !strncmp(arch, "arm64", 5) || !strncmp(arch, "mips64", 6) || > + !strncmp(arch, "parisc64", 8) || !strncmp(arch, "riscv64", 7) || > + !strncmp(arch, "s390x", 5) || !strncmp(arch, "sparc64", 7)) > + kernel_is_64_bit = 1; > + else > + kernel_is_64_bit = 0; > +} > + > void perf_env__exit(struct perf_env *env) > { > int i; > @@ -217,13 +231,14 @@ void perf_env__exit(struct perf_env *env) > zfree(&env->hybrid_cpc_nodes); > } > > -void perf_env__init(struct perf_env *env __maybe_unused) > +void perf_env__init(struct perf_env *env) > { > #ifdef HAVE_LIBBPF_SUPPORT > env->bpf_progs.infos = RB_ROOT; > env->bpf_progs.btfs = RB_ROOT; > init_rwsem(&env->bpf_progs.lock); > #endif > + perf_env__init_kernel_mode(env); perf_env__init() is also used for session->header.env which is not necessarily the current machine. So this initialization could be separate from perf_env__init() to avoid confusion. > } > > int perf_env__set_cmdline(struct perf_env *env, int argc, const char *argv[]) > diff --git a/tools/perf/util/env.h b/tools/perf/util/env.h > index 6824a7423a2d..cc989ff49740 100644 > --- a/tools/perf/util/env.h > +++ b/tools/perf/util/env.h > @@ -139,6 +139,7 @@ enum perf_compress_type { > struct bpf_prog_info_node; > struct btf_node; > > +extern int kernel_is_64_bit; > extern struct perf_env perf_env; > > void perf_env__exit(struct perf_env *env); >
Em Sun, Jul 11, 2021 at 06:41:04PM +0800, Leo Yan escreveu: > It's useful to know that the kernel is running in 32-bit or 64-bit > mode. E.g. We can decide if perf tool is running in compat mode > from this info. > > This patch adds a global variable "kernel_is_64_bit", it's initialized > when a session setups environment, its value is decided by checking the > architecture string. > > Signed-off-by: Leo Yan <leo.yan@linaro.org> > --- > tools/perf/util/env.c | 17 ++++++++++++++++- > tools/perf/util/env.h | 1 + > 2 files changed, 17 insertions(+), 1 deletion(-) > > diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c > index ebc5e9ad35db..345635a2e842 100644 > --- a/tools/perf/util/env.c > +++ b/tools/perf/util/env.c > @@ -11,6 +11,7 @@ > #include <stdlib.h> > #include <string.h> > > +int kernel_is_64_bit; > struct perf_env perf_env; Why can't this be in 'struct perf_env'? - Arnaldo > #ifdef HAVE_LIBBPF_SUPPORT > @@ -172,6 +173,19 @@ static void perf_env__purge_bpf(struct perf_env *env __maybe_unused) > } > #endif // HAVE_LIBBPF_SUPPORT > > +static void perf_env__init_kernel_mode(struct perf_env *env) > +{ > + const char *arch = perf_env__raw_arch(env); > + > + if (!strncmp(arch, "x86_64", 6) || !strncmp(arch, "aarch64", 7) || > + !strncmp(arch, "arm64", 5) || !strncmp(arch, "mips64", 6) || > + !strncmp(arch, "parisc64", 8) || !strncmp(arch, "riscv64", 7) || > + !strncmp(arch, "s390x", 5) || !strncmp(arch, "sparc64", 7)) > + kernel_is_64_bit = 1; > + else > + kernel_is_64_bit = 0; > +} > + > void perf_env__exit(struct perf_env *env) > { > int i; > @@ -217,13 +231,14 @@ void perf_env__exit(struct perf_env *env) > zfree(&env->hybrid_cpc_nodes); > } > > -void perf_env__init(struct perf_env *env __maybe_unused) > +void perf_env__init(struct perf_env *env) > { > #ifdef HAVE_LIBBPF_SUPPORT > env->bpf_progs.infos = RB_ROOT; > env->bpf_progs.btfs = RB_ROOT; > init_rwsem(&env->bpf_progs.lock); > #endif > + perf_env__init_kernel_mode(env); > } > > int perf_env__set_cmdline(struct perf_env *env, int argc, const char *argv[]) > diff --git a/tools/perf/util/env.h b/tools/perf/util/env.h > index 6824a7423a2d..cc989ff49740 100644 > --- a/tools/perf/util/env.h > +++ b/tools/perf/util/env.h > @@ -139,6 +139,7 @@ enum perf_compress_type { > struct bpf_prog_info_node; > struct btf_node; > > +extern int kernel_is_64_bit; > extern struct perf_env perf_env; > > void perf_env__exit(struct perf_env *env); > -- > 2.25.1 >
Hi Arnaldo, Adrian, On Mon, Jul 12, 2021 at 03:14:35PM -0300, Arnaldo Carvalho de Melo wrote: > Em Sun, Jul 11, 2021 at 06:41:04PM +0800, Leo Yan escreveu: > > It's useful to know that the kernel is running in 32-bit or 64-bit > > mode. E.g. We can decide if perf tool is running in compat mode > > from this info. > > > > This patch adds a global variable "kernel_is_64_bit", it's initialized > > when a session setups environment, its value is decided by checking the > > architecture string. > > > > Signed-off-by: Leo Yan <leo.yan@linaro.org> > > --- > > tools/perf/util/env.c | 17 ++++++++++++++++- > > tools/perf/util/env.h | 1 + > > 2 files changed, 17 insertions(+), 1 deletion(-) > > > > diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c > > index ebc5e9ad35db..345635a2e842 100644 > > --- a/tools/perf/util/env.c > > +++ b/tools/perf/util/env.c > > @@ -11,6 +11,7 @@ > > #include <stdlib.h> > > #include <string.h> > > > > +int kernel_is_64_bit; > > struct perf_env perf_env; > > Why can't this be in 'struct perf_env'? Good question. I considered to add it in struct perf_env but finally I used this way; the reason is this variable "kernel_is_64_bit" is only used during recording phase for AUX ring buffer, and don't use it for report. So seems to me it's over complexity to add a new field and just wander if it's necessary to save this field as new feature in the perf header. Combining the comment from Adrian in another email, I think it's good to add a new field "compat_mode" in the struct perf_env, and this field will be initialized in build-record.c. Currently we don't need to save this value into the perf file, if later we need to use this value for decoding phase, then we can add a new feature item to save "compat_mode" into the perf file's header. If you have any different idea, please let me know. Thanks! Leo
> -----Original Message----- > From: Leo Yan <leo.yan@linaro.org> > Sent: Tuesday, July 13, 2021 6:10 PM > To: Arnaldo Carvalho de Melo <acme@kernel.org> > Cc: Hunter, Adrian <adrian.hunter@intel.com>; Peter Zijlstra > <peterz@infradead.org>; Ingo Molnar <mingo@redhat.com>; Mark Rutland > <mark.rutland@arm.com>; Alexander Shishkin > <alexander.shishkin@linux.intel.com>; Jiri Olsa <jolsa@redhat.com>; > Namhyung Kim <namhyung@kernel.org>; Thomas Gleixner > <tglx@linutronix.de>; Borislav Petkov <bp@alien8.de>; x86@kernel.org; H. > Peter Anvin <hpa@zytor.com>; Mathieu Poirier > <mathieu.poirier@linaro.org>; Suzuki K Poulose > <suzuki.poulose@arm.com>; Mike Leach <mike.leach@linaro.org>; linux- > perf-users@vger.kernel.org; linux-kernel@vger.kernel.org; > coresight@lists.linaro.org; linux-arm-kernel@lists.infradead.org > Subject: Re: [PATCH v4 10/11] perf env: Set flag for kernel is 64-bit mode > > Hi Arnaldo, Adrian, > > On Mon, Jul 12, 2021 at 03:14:35PM -0300, Arnaldo Carvalho de Melo wrote: > > Em Sun, Jul 11, 2021 at 06:41:04PM +0800, Leo Yan escreveu: > > > It's useful to know that the kernel is running in 32-bit or 64-bit > > > mode. E.g. We can decide if perf tool is running in compat mode > > > from this info. > > > > > > This patch adds a global variable "kernel_is_64_bit", it's > > > initialized when a session setups environment, its value is decided > > > by checking the architecture string. > > > > > > Signed-off-by: Leo Yan <leo.yan@linaro.org> > > > --- > > > tools/perf/util/env.c | 17 ++++++++++++++++- tools/perf/util/env.h > > > | 1 + > > > 2 files changed, 17 insertions(+), 1 deletion(-) > > > > > > diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c index > > > ebc5e9ad35db..345635a2e842 100644 > > > --- a/tools/perf/util/env.c > > > +++ b/tools/perf/util/env.c > > > @@ -11,6 +11,7 @@ > > > #include <stdlib.h> > > > #include <string.h> > > > > > > +int kernel_is_64_bit; > > > struct perf_env perf_env; > > > > Why can't this be in 'struct perf_env'? > > Good question. I considered to add it in struct perf_env but finally I used this > way; the reason is this variable "kernel_is_64_bit" is only used during > recording phase for AUX ring buffer, and don't use it for report. So seems to > me it's over complexity to add a new field and just wander if it's necessary to > save this field as new feature in the perf header. I think we store the arch, so if the "kernel_is_64_bit" calculation depends only on arch then I guess we don't need a new feature at the moment. > > Combining the comment from Adrian in another email, I think it's good to add > a new field "compat_mode" in the struct perf_env, and this field will be > initialized in build-record.c. Currently we don't need to save this value into > the perf file, if later we need to use this value for decoding phase, then we > can add a new feature item to save "compat_mode" > into the perf file's header. > > If you have any different idea, please let me know. Thanks! > > Leo
Em Tue, Jul 13, 2021 at 05:31:03PM +0000, Hunter, Adrian escreveu: > > On Mon, Jul 12, 2021 at 03:14:35PM -0300, Arnaldo Carvalho de Melo wrote: > > > Em Sun, Jul 11, 2021 at 06:41:04PM +0800, Leo Yan escreveu: > > > > +++ b/tools/perf/util/env.c > > > > @@ -11,6 +11,7 @@ > > > > #include <stdlib.h> > > > > #include <string.h> > > > > +int kernel_is_64_bit; > > > > struct perf_env perf_env; > > > Why can't this be in 'struct perf_env'? > > Good question. I considered to add it in struct perf_env but finally I used this > > way; the reason is this variable "kernel_is_64_bit" is only used during > > recording phase for AUX ring buffer, and don't use it for report. So seems to > > me it's over complexity to add a new field and just wander if it's necessary to > > save this field as new feature in the perf header. > I think we store the arch, so if the "kernel_is_64_bit" calculation depends only on arch > then I guess we don't need a new feature at the moment. So, I wasn't suggesting to add this info to the perf.data file header, just to the in-memory 'struct perf_env'. And also we should avoid unconditionally initializing things that we may never need, please structure it as: static void perf_env__init_kernel_mode(struct perf_env *env) { const char *arch = perf_env__raw_arch(env); if (!strncmp(arch, "x86_64", 6) || !strncmp(arch, "aarch64", 7) || !strncmp(arch, "arm64", 5) || !strncmp(arch, "mips64", 6) || !strncmp(arch, "parisc64", 8) || !strncmp(arch, "riscv64", 7) || !strncmp(arch, "s390x", 5) || !strncmp(arch, "sparc64", 7)) kernel_is_64_bit = 1; else kernel_is_64_bit = 0; } void perf_env__init(struct perf_env *env) { ... env->kernel_is_64_bit = -1; ... } bool perf_env__kernel_is_64_bit(struct perf_env *env) { if (env->kernel_is_64_bit == -1) perf_env__init_kernel_mode(env); return env->kernel_is_64_bit; } One thing in my TODO is to crack down on the tons of initializations perf does unconditionally, last time I looked there are lots :-\ - Arnaldo > > Combining the comment from Adrian in another email, I think it's good to add > > a new field "compat_mode" in the struct perf_env, and this field will be > > initialized in build-record.c. Currently we don't need to save this value into > > the perf file, if later we need to use this value for decoding phase, then we > > can add a new feature item to save "compat_mode" > > into the perf file's header. > > If you have any different idea, please let me know. Thanks!
Em Wed, Jul 14, 2021 at 10:59:49AM -0300, Arnaldo Carvalho de Melo escreveu: > Em Tue, Jul 13, 2021 at 05:31:03PM +0000, Hunter, Adrian escreveu: > > > On Mon, Jul 12, 2021 at 03:14:35PM -0300, Arnaldo Carvalho de Melo wrote: > > > > Em Sun, Jul 11, 2021 at 06:41:04PM +0800, Leo Yan escreveu: > > > > > +++ b/tools/perf/util/env.c > > > > > @@ -11,6 +11,7 @@ > > > > > #include <stdlib.h> > > > > > #include <string.h> > > > > > > +int kernel_is_64_bit; > > > > > struct perf_env perf_env; > > > > > Why can't this be in 'struct perf_env'? > > > > Good question. I considered to add it in struct perf_env but finally I used this > > > way; the reason is this variable "kernel_is_64_bit" is only used during > > > recording phase for AUX ring buffer, and don't use it for report. So seems to > > > me it's over complexity to add a new field and just wander if it's necessary to > > > save this field as new feature in the perf header. > > > I think we store the arch, so if the "kernel_is_64_bit" calculation depends only on arch > > then I guess we don't need a new feature at the moment. > > So, I wasn't suggesting to add this info to the perf.data file header, > just to the in-memory 'struct perf_env'. > > And also we should avoid unconditionally initializing things that we may > never need, please structure it as: Oops, forgot these: > static void perf_env__init_kernel_mode(struct perf_env *env) > { > const char *arch = perf_env__raw_arch(env); > > if (!strncmp(arch, "x86_64", 6) || !strncmp(arch, "aarch64", 7) || > !strncmp(arch, "arm64", 5) || !strncmp(arch, "mips64", 6) || > !strncmp(arch, "parisc64", 8) || !strncmp(arch, "riscv64", 7) || > !strncmp(arch, "s390x", 5) || !strncmp(arch, "sparc64", 7)) > kernel_is_64_bit = 1; env->kernel_is_64_bit = 1; > else > kernel_is_64_bit = 0; env->kernel_is_64_bit = 0; > } > > > void perf_env__init(struct perf_env *env) > { > ... > env->kernel_is_64_bit = -1; > ... > } > > bool perf_env__kernel_is_64_bit(struct perf_env *env) > { > if (env->kernel_is_64_bit == -1) > perf_env__init_kernel_mode(env); > > return env->kernel_is_64_bit; > } > > One thing in my TODO is to crack down on the tons of initializations > perf does unconditionally, last time I looked there are lots :-\ > > - Arnaldo > > > > Combining the comment from Adrian in another email, I think it's good to add > > > a new field "compat_mode" in the struct perf_env, and this field will be > > > initialized in build-record.c. Currently we don't need to save this value into > > > the perf file, if later we need to use this value for decoding phase, then we > > > can add a new feature item to save "compat_mode" > > > into the perf file's header. > > > > If you have any different idea, please let me know. Thanks!
Hi Arnaldo, On Wed, Jul 14, 2021 at 11:00:44AM -0300, Arnaldo Carvalho de Melo wrote: [...] > > So, I wasn't suggesting to add this info to the perf.data file header, > > just to the in-memory 'struct perf_env'. > > > > And also we should avoid unconditionally initializing things that we may > > never need, please structure it as: > > Oops, forgot these: > > > static void perf_env__init_kernel_mode(struct perf_env *env) > > { > > const char *arch = perf_env__raw_arch(env); > > > > if (!strncmp(arch, "x86_64", 6) || !strncmp(arch, "aarch64", 7) || > > !strncmp(arch, "arm64", 5) || !strncmp(arch, "mips64", 6) || > > !strncmp(arch, "parisc64", 8) || !strncmp(arch, "riscv64", 7) || > > !strncmp(arch, "s390x", 5) || !strncmp(arch, "sparc64", 7)) > > kernel_is_64_bit = 1; > env->kernel_is_64_bit = 1; > > else > > kernel_is_64_bit = 0; > env->kernel_is_64_bit = 0; > > } > > > > > > void perf_env__init(struct perf_env *env) > > { > > ... > > env->kernel_is_64_bit = -1; > > ... > > } > > > > bool perf_env__kernel_is_64_bit(struct perf_env *env) > > { > > if (env->kernel_is_64_bit == -1) > > perf_env__init_kernel_mode(env); > > > > return env->kernel_is_64_bit; > > } Thanks a lot for the suggestion; this is much clear for me, will spin new patch set by following it. Sorry for slow response due to my bandwidth was occupied by a task in hand. Thanks, Leo
diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c index ebc5e9ad35db..345635a2e842 100644 --- a/tools/perf/util/env.c +++ b/tools/perf/util/env.c @@ -11,6 +11,7 @@ #include <stdlib.h> #include <string.h> +int kernel_is_64_bit; struct perf_env perf_env; #ifdef HAVE_LIBBPF_SUPPORT @@ -172,6 +173,19 @@ static void perf_env__purge_bpf(struct perf_env *env __maybe_unused) } #endif // HAVE_LIBBPF_SUPPORT +static void perf_env__init_kernel_mode(struct perf_env *env) +{ + const char *arch = perf_env__raw_arch(env); + + if (!strncmp(arch, "x86_64", 6) || !strncmp(arch, "aarch64", 7) || + !strncmp(arch, "arm64", 5) || !strncmp(arch, "mips64", 6) || + !strncmp(arch, "parisc64", 8) || !strncmp(arch, "riscv64", 7) || + !strncmp(arch, "s390x", 5) || !strncmp(arch, "sparc64", 7)) + kernel_is_64_bit = 1; + else + kernel_is_64_bit = 0; +} + void perf_env__exit(struct perf_env *env) { int i; @@ -217,13 +231,14 @@ void perf_env__exit(struct perf_env *env) zfree(&env->hybrid_cpc_nodes); } -void perf_env__init(struct perf_env *env __maybe_unused) +void perf_env__init(struct perf_env *env) { #ifdef HAVE_LIBBPF_SUPPORT env->bpf_progs.infos = RB_ROOT; env->bpf_progs.btfs = RB_ROOT; init_rwsem(&env->bpf_progs.lock); #endif + perf_env__init_kernel_mode(env); } int perf_env__set_cmdline(struct perf_env *env, int argc, const char *argv[]) diff --git a/tools/perf/util/env.h b/tools/perf/util/env.h index 6824a7423a2d..cc989ff49740 100644 --- a/tools/perf/util/env.h +++ b/tools/perf/util/env.h @@ -139,6 +139,7 @@ enum perf_compress_type { struct bpf_prog_info_node; struct btf_node; +extern int kernel_is_64_bit; extern struct perf_env perf_env; void perf_env__exit(struct perf_env *env);
It's useful to know that the kernel is running in 32-bit or 64-bit mode. E.g. We can decide if perf tool is running in compat mode from this info. This patch adds a global variable "kernel_is_64_bit", it's initialized when a session setups environment, its value is decided by checking the architecture string. Signed-off-by: Leo Yan <leo.yan@linaro.org> --- tools/perf/util/env.c | 17 ++++++++++++++++- tools/perf/util/env.h | 1 + 2 files changed, 17 insertions(+), 1 deletion(-)