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    SubjectRe: [PATCH 3/3] Add name fields in shrinker tracepoint definitions
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    > On Jul 13, 2016, at 6:05 AM, Tony Jones <tonyj@suse.de> wrote:
    >
    > On 07/11/2016 07:18 AM, Vlastimil Babka wrote:
    >> On 07/09/2016 11:05 AM, Janani Ravichandran wrote:
    >>>
    >>> TP_fast_assign(
    >>> + __entry->name = shr->name;
    >>> __entry->shr = shr;
    >>> __entry->shrink = shr->scan_objects;
    >>> __entry->nid = sc->nid;
    >>> @@ -214,7 +216,8 @@ TRACE_EVENT(mm_shrink_slab_start,
    >>> __entry->total_scan = total_scan;
    >>> ),
    >>>
    >>> - TP_printk("%pF %p: nid: %d objects to shrink %ld gfp_flags %s pgs_scanned %ld lru_pgs %ld cache items %ld delta %lld total_scan %ld",
    >>> + TP_printk("name: %s %pF %p: nid: %d objects to shrink %ld gfp_flags %s pgs_scanned %ld lru_pgs %ld cache items %ld delta %lld total_scan %ld",
    >>> + __entry->name,
    >>
    >> Is this legal to do when printing is not done via the /sys ... file
    >> itself, but raw data is collected and then printed by e.g. trace-cmd?
    >> How can it possibly interpret the "char *" kernel pointer?
    >
    > I actually had a similar patch set to this, I was going to post it but Janani beat me to it ;-)
    >
    > Vlastimil is correct, I'll attach my patch below so you can see the difference. Otherwise you won't get correct behavior passing through perf.

    Thanks for that! I will have a look at it.
    >
    >
    > I also have a patch which adds a similar latency script (python) but interfaces it into the perf script setup.

    I’m looking for pointers for writing latency scripts using tracepoints as I’m new to it. Can I have a look at yours, please?

    Thanks :)

    Janani.
    >
    > Tony
    >
    > ---
    >
    > Pass shrinker name in shrink slab tracepoints
    >
    > Signed-off-by: Tony Jones <tonyj@suse.de>
    > ---
    > include/trace/events/vmscan.h | 12 ++++++++++--
    > 1 file changed, 10 insertions(+), 2 deletions(-)
    >
    > diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h
    > index 0101ef3..0a15948 100644
    > --- a/include/trace/events/vmscan.h
    > +++ b/include/trace/events/vmscan.h
    > @@ -16,6 +16,8 @@
    > #define RECLAIM_WB_SYNC 0x0004u /* Unused, all reclaim async */
    > #define RECLAIM_WB_ASYNC 0x0008u
    >
    > +#define SHRINKER_NAME_LEN (size_t)32
    > +
    > #define show_reclaim_flags(flags) \
    > (flags) ? __print_flags(flags, "|", \
    > {RECLAIM_WB_ANON, "RECLAIM_WB_ANON"}, \
    > @@ -190,6 +192,7 @@ TRACE_EVENT(mm_shrink_slab_start,
    >
    > TP_STRUCT__entry(
    > __field(struct shrinker *, shr)
    > + __array(char, name, SHRINKER_NAME_LEN)
    > __field(void *, shrink)
    > __field(int, nid)
    > __field(long, nr_objects_to_shrink)
    > @@ -203,6 +206,7 @@ TRACE_EVENT(mm_shrink_slab_start,
    >
    > TP_fast_assign(
    > __entry->shr = shr;
    > + strlcpy(__entry->name, shr->name, SHRINKER_NAME_LEN);
    > __entry->shrink = shr->scan_objects;
    > __entry->nid = sc->nid;
    > __entry->nr_objects_to_shrink = nr_objects_to_shrink;
    > @@ -214,9 +218,10 @@ TRACE_EVENT(mm_shrink_slab_start,
    > __entry->total_scan = total_scan;
    > ),
    >
    > - TP_printk("%pF %p: nid: %d objects to shrink %ld gfp_flags %s pgs_scanned %ld lru_pgs %ld cache items %ld delta %lld total_scan %ld",
    > + TP_printk("%pF %p(%s): nid: %d objects to shrink %ld gfp_flags %s pgs_scanned %ld lru_pgs %ld cache items %ld delta %lld total_scan %ld",
    > __entry->shrink,
    > __entry->shr,
    > + __entry->name,
    > __entry->nid,
    > __entry->nr_objects_to_shrink,
    > show_gfp_flags(__entry->gfp_flags),
    > @@ -236,6 +241,7 @@ TRACE_EVENT(mm_shrink_slab_end,
    >
    > TP_STRUCT__entry(
    > __field(struct shrinker *, shr)
    > + __array(char, name, SHRINKER_NAME_LEN)
    > __field(int, nid)
    > __field(void *, shrink)
    > __field(long, unused_scan)
    > @@ -246,6 +252,7 @@ TRACE_EVENT(mm_shrink_slab_end,
    >
    > TP_fast_assign(
    > __entry->shr = shr;
    > + strlcpy(__entry->name, shr->name, SHRINKER_NAME_LEN);
    > __entry->nid = nid;
    > __entry->shrink = shr->scan_objects;
    > __entry->unused_scan = unused_scan_cnt;
    > @@ -254,9 +261,10 @@ TRACE_EVENT(mm_shrink_slab_end,
    > __entry->total_scan = total_scan;
    > ),
    >
    > - TP_printk("%pF %p: nid: %d unused scan count %ld new scan count %ld total_scan %ld last shrinker return val %d",
    > + TP_printk("%pF %p(%s): nid: %d unused scan count %ld new scan count %ld total_scan %ld last shrinker return val %d",
    > __entry->shrink,
    > __entry->shr,
    > + __entry->name,
    > __entry->nid,
    > __entry->unused_scan,
    > __entry->new_scan,
    >
    >

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