lkml.org 
[lkml]   [2020]   [Apr]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[tip: perf/core] perf machine: Refine the function for LBR call stack reconstruction
    The following commit has been merged into the perf/core branch of tip:

    Commit-ID: e48b8311ca4538ec716196a1625812b045999f21
    Gitweb: https://git.kernel.org/tip/e48b8311ca4538ec716196a1625812b045999f21
    Author: Kan Liang <kan.liang@linux.intel.com>
    AuthorDate: Thu, 19 Mar 2020 13:25:06 -07:00
    Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
    CommitterDate: Sat, 18 Apr 2020 09:05:00 -03:00

    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>
    ---
    tools/perf/util/machine.c | 111 +++++++++++++++++++++++++------------
    1 file changed, 76 insertions(+), 35 deletions(-)

    diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
    index be1bd92..0da540e 100644
    --- a/tools/perf/util/machine.c
    +++ b/tools/perf/util/machine.c
    @@ -2214,6 +2214,7 @@ static int resolve_lbr_callchain_sample(struct thread *thread,
    bool branch;
    struct branch_flags *flags;
    int mix_chain_nr;
    + int err;

    for (i = 0; i < chain_nr; i++) {
    if (chain->ips[i] == PERF_CONTEXT_USER)
    @@ -2239,50 +2240,90 @@ static int resolve_lbr_callchain_sample(struct thread *thread,
    */
    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 {
    - 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;
    - }
    + if (callchain_param.order == ORDER_CALLEE) {
    + /* Add kernel ip */
    + for (j = 0; j < i + 1; j++) {
    + ip = chain->ips[j];
    + branch = false;
    + flags = NULL;
    + err = add_callchain_ip(thread, cursor, parent,
    + root_al, &cpumode, ip,
    + branch, flags, NULL,
    + branch_from);
    + if (err)
    + goto error;
    }
    + /* Add LBR ip from first entries.to */
    + 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)
    + goto error;

    + /* Add LBR ip from entries.from one by one. */
    + for (j = i + 2; j < mix_chain_nr; j++) {
    + k = j - i - 2;
    + ip = entries[k].from;
    + branch = true;
    + flags = &entries[k].flags;
    +
    + err = add_callchain_ip(thread, cursor, parent,
    + root_al, &cpumode, ip,
    + branch, flags, NULL,
    + branch_from);
    + if (err)
    + goto error;
    + }
    + } else {
    + /* Add LBR ip from entries.from one by one. */
    + for (j = 0; j < lbr_nr; j++) {
    + k = lbr_nr - j - 1;
    + ip = entries[k].from;
    + branch = true;
    + flags = &entries[k].flags;
    +
    + err = add_callchain_ip(thread, cursor, parent,
    + root_al, &cpumode, ip,
    + branch, flags, NULL,
    + branch_from);
    + if (err)
    + goto error;
    + }
    +
    + /* Add LBR ip from first entries.to */
    + 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;
    + goto error;
    +
    + /* Add kernel ip */
    + for (j = lbr_nr + 1; j < mix_chain_nr; j++) {
    + ip = chain->ips[i + 1 - (j - lbr_nr)];
    + branch = false;
    + flags = NULL;
    + err = add_callchain_ip(thread, cursor, parent,
    + root_al, &cpumode, ip,
    + branch, flags, NULL,
    + branch_from);
    + if (err)
    + goto error;
    + }
    }
    return 1;
    +
    +error:
    + return (err < 0) ? err : 0;
    }

    static int find_prev_cpumode(struct ip_callchain *chain, struct thread *thread,
    \
     
     \ /
      Last update: 2020-04-22 14:22    [W:4.112 / U:0.012 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site