perf machine: Refine the function for LBR call stack reconstruction
LBR only collect the user call stack. To reconstruct a call stack, both
kernel call stack and user call stack are required. The function
resolve_lbr_callchain_sample() mix the kernel call stack and user call
stack.
Now, with the help of HW idx, perf tool can reconstruct a more complete
call stack by adding some user call stack from previous sample. However,
current implementation is hard to be extended to support it.
Current code path for resolve_lbr_callchain_sample()
for (j = 0; j < mix_chain_nr; j++) {
if (ORDER_CALLEE) {
if (kernel callchain)
Fill callchain info
else if (LBR callchain)
Fill callchain info
} else {
if (LBR callchain)
Fill callchain info
else if (kernel callchain)
Fill callchain info
}
add_callchain_ip();
}
With the patch,
if (ORDER_CALLEE) {
for (j = 0; j < NUM of kernel callchain) {
Fill callchain info
add_callchain_ip();
}
for (; j < mix_chain_nr) {
Fill callchain info
add_callchain_ip();
}
} else {
for (; j < NUM of LBR callchain) {
Fill callchain info
add_callchain_ip();
}
for (j = 0; j < mix_chain_nr) {
Fill callchain info
add_callchain_ip();
}
}
No functional changes.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Pavel Gerasimov <pavel.gerasimov@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vitaly Slobodskoy <vitaly.slobodskoy@intel.com>
Link: http://lore.kernel.org/lkml/20200319202517.23423-7-kan.liang@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Kan Liang
Arnaldo Carvalho de Melo
Родитель
f8603267bf
Коммит
e48b8311ca
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@ -2214,6 +2214,7 @@ static int resolve_lbr_callchain_sample(struct thread *thread,
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bool branch;
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struct branch_flags *flags;
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int mix_chain_nr;
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int err;
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for (i = 0; i < chain_nr; i++) {
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if (chain->ips[i] == PERF_CONTEXT_USER)
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@ -2239,50 +2240,90 @@ static int resolve_lbr_callchain_sample(struct thread *thread,
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*/
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mix_chain_nr = i + 1 + lbr_nr + 1;
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for (j = 0; j < mix_chain_nr; j++) {
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int err;
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branch = false;
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flags = NULL;
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if (callchain_param.order == ORDER_CALLEE) {
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if (j < i + 1)
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ip = chain->ips[j];
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else if (j > i + 1) {
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k = j - i - 2;
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ip = entries[k].from;
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branch = true;
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flags = &entries[k].flags;
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} else {
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ip = entries[0].to;
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branch = true;
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flags = &entries[0].flags;
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branch_from = entries[0].from;
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}
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} else {
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if (j < lbr_nr) {
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k = lbr_nr - j - 1;
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ip = entries[k].from;
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branch = true;
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flags = &entries[k].flags;
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} else if (j > lbr_nr)
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ip = chain->ips[i + 1 - (j - lbr_nr)];
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else {
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ip = entries[0].to;
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branch = true;
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flags = &entries[0].flags;
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branch_from = entries[0].from;
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}
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if (callchain_param.order == ORDER_CALLEE) {
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/* Add kernel ip */
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for (j = 0; j < i + 1; j++) {
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ip = chain->ips[j];
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branch = false;
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flags = NULL;
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err = add_callchain_ip(thread, cursor, parent,
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root_al, &cpumode, ip,
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branch, flags, NULL,
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branch_from);
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if (err)
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goto error;
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}
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/* Add LBR ip from first entries.to */
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ip = entries[0].to;
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branch = true;
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flags = &entries[0].flags;
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branch_from = entries[0].from;
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err = add_callchain_ip(thread, cursor, parent,
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root_al, &cpumode, ip,
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branch, flags, NULL,
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branch_from);
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if (err)
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return (err < 0) ? err : 0;
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goto error;
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/* Add LBR ip from entries.from one by one. */
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for (j = i + 2; j < mix_chain_nr; j++) {
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k = j - i - 2;
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ip = entries[k].from;
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branch = true;
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flags = &entries[k].flags;
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err = add_callchain_ip(thread, cursor, parent,
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root_al, &cpumode, ip,
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branch, flags, NULL,
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branch_from);
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if (err)
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goto error;
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}
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} else {
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/* Add LBR ip from entries.from one by one. */
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for (j = 0; j < lbr_nr; j++) {
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k = lbr_nr - j - 1;
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ip = entries[k].from;
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branch = true;
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flags = &entries[k].flags;
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err = add_callchain_ip(thread, cursor, parent,
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root_al, &cpumode, ip,
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branch, flags, NULL,
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branch_from);
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if (err)
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goto error;
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}
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/* Add LBR ip from first entries.to */
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ip = entries[0].to;
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branch = true;
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flags = &entries[0].flags;
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branch_from = entries[0].from;
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err = add_callchain_ip(thread, cursor, parent,
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root_al, &cpumode, ip,
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branch, flags, NULL,
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branch_from);
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if (err)
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goto error;
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/* Add kernel ip */
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for (j = lbr_nr + 1; j < mix_chain_nr; j++) {
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ip = chain->ips[i + 1 - (j - lbr_nr)];
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branch = false;
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flags = NULL;
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err = add_callchain_ip(thread, cursor, parent,
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root_al, &cpumode, ip,
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branch, flags, NULL,
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branch_from);
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if (err)
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goto error;
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}
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}
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return 1;
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error:
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return (err < 0) ? err : 0;
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}
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static int find_prev_cpumode(struct ip_callchain *chain, struct thread *thread,
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