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
-
Arnaldo Carvalho de Melo -
Leo Yan