Re: [PATCH 3/3] Add name fields in shrinker tracepoint definitions

Janani Ravichandran
2016-07-13T06:17:28Z

> 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,
>
>