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Date: Wed, 18 Mar 2020 16:50:45 -0300
From: Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
To: kan.liang@...ux.intel.com
Cc: jolsa@...hat.com, peterz@...radead.org, mingo@...hat.com,
linux-kernel@...r.kernel.org, namhyung@...nel.org,
adrian.hunter@...el.com, mathieu.poirier@...aro.org,
ravi.bangoria@...ux.ibm.com, alexey.budankov@...ux.intel.com,
vitaly.slobodskoy@...el.com, pavel.gerasimov@...el.com,
mpe@...erman.id.au, eranian@...gle.com, ak@...ux.intel.com
Subject: Re: [PATCH V3 05/17] perf machine: Remove the indent in
resolve_lbr_callchain_sample
Em Fri, Mar 13, 2020 at 11:33:07AM -0700, kan.liang@...ux.intel.com escreveu:
> From: Kan Liang <kan.liang@...ux.intel.com>
>
> The indent is unnecessary in resolve_lbr_callchain_sample.
> Removing it will make the following patch simpler.
>
> Current code path for resolve_lbr_callchain_sample()
>
> /* LBR only affects the user callchain */
> if (i != chain_nr) {
> body of the function
> ....
> return 1;
> }
>
> return 0;
>
> With the patch,
>
> /* LBR only affects the user callchain */
> if (i == chain_nr)
> return 0;
>
> body of the function
> ...
> return 1;
>
> No functional changes.
Thanks for doing this,
- Arnaldo
> Reviewed-by: Andi Kleen <ak@...ux.intel.com>
> Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
> ---
> tools/perf/util/machine.c | 123 +++++++++++++++++++-------------------
> 1 file changed, 63 insertions(+), 60 deletions(-)
>
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index fd14f1489802..9021e5b6a2a9 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -2177,6 +2177,12 @@ static int resolve_lbr_callchain_sample(struct thread *thread,
> int chain_nr = min(max_stack, (int)chain->nr), i;
> u8 cpumode = PERF_RECORD_MISC_USER;
> u64 ip, branch_from = 0;
> + struct branch_stack *lbr_stack;
> + struct branch_entry *entries;
> + int lbr_nr, j, k;
> + bool branch;
> + struct branch_flags *flags;
> + int mix_chain_nr;
>
> for (i = 0; i < chain_nr; i++) {
> if (chain->ips[i] == PERF_CONTEXT_USER)
> @@ -2184,71 +2190,68 @@ static int resolve_lbr_callchain_sample(struct thread *thread,
> }
>
> /* LBR only affects the user callchain */
> - if (i != chain_nr) {
> - struct branch_stack *lbr_stack = sample->branch_stack;
> - struct branch_entry *entries = perf_sample__branch_entries(sample);
> - int lbr_nr = lbr_stack->nr, j, k;
> - bool branch;
> - struct branch_flags *flags;
> - /*
> - * LBR callstack can only get user call chain.
> - * The mix_chain_nr is kernel call chain
> - * number plus LBR user call chain number.
> - * i is kernel call chain number,
> - * 1 is PERF_CONTEXT_USER,
> - * lbr_nr + 1 is the user call chain number.
> - * For details, please refer to the comments
> - * in callchain__printf
> - */
> - int mix_chain_nr = i + 1 + lbr_nr + 1;
> -
> - for (j = 0; j < mix_chain_nr; j++) {
> - int err;
> - branch = false;
> - flags = NULL;
> + if (i == chain_nr)
> + return 0;
>
> - if (callchain_param.order == ORDER_CALLEE) {
> - if (j < i + 1)
> - ip = chain->ips[j];
> - else if (j > i + 1) {
> - k = j - i - 2;
> - ip = entries[k].from;
> - branch = true;
> - flags = &entries[k].flags;
> - } else {
> - ip = entries[0].to;
> - branch = true;
> - flags = &entries[0].flags;
> - branch_from = entries[0].from;
> - }
> + lbr_stack = sample->branch_stack;
> + entries = perf_sample__branch_entries(sample);
> + lbr_nr = lbr_stack->nr;
> + /*
> + * LBR callstack can only get user call chain.
> + * The mix_chain_nr is kernel call chain
> + * number plus LBR user call chain number.
> + * i is kernel call chain number,
> + * 1 is PERF_CONTEXT_USER,
> + * lbr_nr + 1 is the user call chain number.
> + * For details, please refer to the comments
> + * in callchain__printf
> + */
> + mix_chain_nr = i + 1 + lbr_nr + 1;
> +
> + for (j = 0; j < mix_chain_nr; j++) {
> + int err;
> +
> + branch = false;
> + flags = NULL;
> +
> + if (callchain_param.order == ORDER_CALLEE) {
> + if (j < i + 1)
> + ip = chain->ips[j];
> + else if (j > i + 1) {
> + k = j - i - 2;
> + ip = entries[k].from;
> + branch = true;
> + flags = &entries[k].flags;
> } else {
> - if (j < lbr_nr) {
> - k = lbr_nr - j - 1;
> - ip = entries[k].from;
> - branch = true;
> - flags = &entries[k].flags;
> - }
> - else if (j > lbr_nr)
> - ip = chain->ips[i + 1 - (j - lbr_nr)];
> - else {
> - ip = entries[0].to;
> - branch = true;
> - flags = &entries[0].flags;
> - branch_from = entries[0].from;
> - }
> + ip = entries[0].to;
> + branch = true;
> + flags = &entries[0].flags;
> + branch_from = entries[0].from;
> + }
> + } else {
> + if (j < lbr_nr) {
> + k = lbr_nr - j - 1;
> + ip = entries[k].from;
> + branch = true;
> + flags = &entries[k].flags;
> + } else if (j > lbr_nr)
> + ip = chain->ips[i + 1 - (j - lbr_nr)];
> + else {
> + ip = entries[0].to;
> + branch = true;
> + flags = &entries[0].flags;
> + branch_from = entries[0].from;
> }
> -
> - err = add_callchain_ip(thread, cursor, parent,
> - root_al, &cpumode, ip,
> - branch, flags, NULL,
> - branch_from);
> - if (err)
> - return (err < 0) ? err : 0;
> }
> - return 1;
> - }
>
> - return 0;
> + err = add_callchain_ip(thread, cursor, parent,
> + root_al, &cpumode, ip,
> + branch, flags, NULL,
> + branch_from);
> + if (err)
> + return (err < 0) ? err : 0;
> + }
> + return 1;
> }
>
> static int find_prev_cpumode(struct ip_callchain *chain, struct thread *thread,
> --
> 2.17.1
>
--
- Arnaldo
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