Re: [PATCH perf/core 00/22] perf refcnt debugger API and fixes

From: Wangnan (F)
Date: Thu Dec 10 2015 - 21:58:36 EST




On 2015/12/11 10:42, Wangnan (F) wrote:


On 2015/12/11 10:15, åæéå / HIRAMATUïMASAMI wrote:
From: 'Arnaldo Carvalho de Melo' [mailto:acme@xxxxxxxxxx]
But this requires having these special refcnt__ routines, that will make
tools/perf/ code patterns for reference counts look different that the
refcount patterns in the kernel :-\
BTW, I think even without the refcnt debugger, we'd better introduce this
kind API to unify the refcnt operation in perf code. As I said, we have many
miscodings on current implementation. Unifying the API can enforce developers
to avoid such miscodings.

Thank you,


I tried this problem in another way, I'd like to share it here.

First: create two uprobes:

# ./perf probe --exec /home/wangnan/perf dso__new%return %ax
Added new event:
probe_perf:dso__new (on dso__new%return in /home/wangnan/perf with %ax)

You can now use it in all perf tools, such as:

perf record -e probe_perf:dso__new -aR sleep 1

# ./perf probe --exec /home/wangnan/perf dso__delete dso
Added new event:
probe_perf:dso__delete (on dso__delete in /home/wangnan/perf with dso)

You can now use it in all perf tools, such as:

perf record -e probe_perf:dso__delete -aR sleep 1


Then start test:

# ./perf record -g -e probe_perf:dso__new -e probe_perf:dso__delete ./perf probe vfs_read
Added new event:
probe:vfs_read (on vfs_read)

You can now use it in all perf tools, such as:

perf record -e probe:vfs_read -aR sleep 1

[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.048 MB perf.data (178 samples) ]


From the perf report result I know two dso objects are leak:

90 probe_perf:dso__new `
88 probe_perf:dso__delete


The above result is gotten from yesterday's perf/core. I also tried
today's perf/core and get:

90 probe_perf:dso__new `
90 probe_perf:dso__delete

So we fix these leak.

Thank you.

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