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    SubjectRe: [PATCH 3/6] perf tools: Reorganize some structs to save space
    Em Thu, Apr 08, 2010 at 05:11:49PM +0200, Peter Zijlstra escreveu:
    > On Thu, 2010-04-08 at 11:38 -0300, Arnaldo Carvalho de Melo wrote:
    > > @@ -68,11 +68,11 @@ struct sample_data {
    > > u64 addr;
    > > u64 id;
    > > u64 stream_id;
    > > - u32 cpu;
    > > u64 period;
    > > - struct ip_callchain *callchain;
    > > + u32 cpu;
    > > u32 raw_size;
    > > void *raw_data;
    > > + struct ip_callchain *callchain;
    > > };
    >
    > If that is a struct that is to match a kernel produced record then this
    > is utterly broken.

    No, it is not, it is filled in userspace:

    tools/perf/util/event.c:

    int event__parse_sample(event_t *event, u64 type, struct sample_data *data)
    {
    u64 *array = event->sample.array;

    if (type & PERF_SAMPLE_IP) {
    data->ip = event->ip.ip;
    array++;
    }

    if (type & PERF_SAMPLE_TID) {
    u32 *p = (u32 *)array;
    data->pid = p[0];
    data->tid = p[1];
    array++;
    }

    if (type & PERF_SAMPLE_TIME) {
    data->time = *array;
    array++;
    }
    <SNIP>

    We can reorder it at will and decoupled from any kernel changes.

    - Arnaldo


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