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Date: Mon, 29 Apr 2024 16:16:59 -0300
From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Ian Rogers <irogers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>,
	Namhyung Kim <namhyung@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@kernel.org>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Kan Liang <kan.liang@linux.intel.com>,
	James Clark <james.clark@arm.com>,
	Athira Rajeev <atrajeev@linux.vnet.ibm.com>,
	Colin Ian King <colin.i.king@gmail.com>,
	nabijaczleweli@nabijaczleweli.xyz, Leo Yan <leo.yan@linux.dev>,
	Song Liu <song@kernel.org>,
	Ilkka Koskinen <ilkka@os.amperecomputing.com>,
	Ben Gainey <ben.gainey@arm.com>,
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	Thomas Richter <tmricht@linux.ibm.com>,
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	Dima Kogan <dima@secretsauce.net>,
	zhaimingbing <zhaimingbing@cmss.chinamobile.com>,
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	Tiezhu Yang <yangtiezhu@loongson.cn>,
	Yang Jihong <yangjihong1@huawei.com>,
	Chengen Du <chengen.du@canonical.com>,
	linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 0/7] dso/dsos memory savings and clean up
Message-ID: <Zi_yKzGMoDU0-L3K@x1>
References: <20240429184614.1224041-1-irogers@google.com>
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In-Reply-To: <20240429184614.1224041-1-irogers@google.com>

On Mon, Apr 29, 2024 at 11:46:07AM -0700, Ian Rogers wrote:
> 7 more patches from:
> https://lore.kernel.org/lkml/20240202061532.1939474-1-irogers@google.com/
> a near half year old adventure in trying to lower perf's dynamic
> memory use. Bits like the memory overhead of opendir are on the
> sidelines for now, too much fighting over how
> distributions/C-libraries present getdents. These changes are more
> good old fashioned replace an rb-tree with a sorted array and add
> reference count tracking.
> 
> The changes migrate dsos code, the collection of dso structs, more
> into the dsos.c/dsos.h files. As with maps and threads, this is done
> so the internals can be changed - replacing a linked list (for fast
> iteration) and an rb-tree (for fast finds) with a lazily sorted
> array. The complexity of operations remain roughly the same, although
> iterating an array is likely faster than iterating a linked list, the
Th> memory usage is at least reduced by half.
> 
> As fixing the memory usage necessitates changing operations like find,
> modify these operations so that they increment the reference count to
> avoid races like a find in dsos and a remove. Similarly tighten up
> lock usage so that operations working on dsos state hold the
> appropriate lock. Note, since this series is partially applied in the
> perf-tools-next tree currently some memory leaks have been introduced.
> 
> v5. Rebase, adding use of accessors to dso as necessary. Previous
>     versions were all rebases or dropping merged patches.

So, on an Intel machine:

⬢[acme@toolbox perf-tools-next]$ git log --oneline -8
fb401385575211e6 (HEAD -> perf-tools-next) perf dso: Use container_of to avoid a pointer in 'struct dso_data'
0fe118d129ab1c77 perf dso: Reference counting related fixes
35e44adf6103a407 perf dso: Add reference count checking and accessor functions
35673675ebbbac5d perf dsos: Switch hand code to bsearch()
654d60f2f5c737cd perf dsos: Remove __dsos__findnew_link_by_longname_id()
94b0ba802e090b66 perf dsos: Remove __dsos__addnew()
47692286dd856469 perf dsos: Switch backing storage to array from rbtree/list
8c618b58c89ce4c2 (perf-tools-next.korg/perf-tools-next, acme.korg/perf-tools-next) perf test: Reintroduce -p/--parallel and make -S/--sequential the default
⬢[acme@toolbox perf-tools-next]$

When I'm at:

8c618b58c89ce4c2 (perf-tools-next.korg/perf-tools-next, acme.korg/perf-tools-next) perf test: Reintroduce -p/--parallel and make -S/--sequential the default

root@x1:~# perf -v
perf version 6.9.rc5.g8c618b58c89c
root@x1:~# perf test "lock contention"
 87: kernel lock contention analysis test                            : Ok
root@x1:~# perf test "lock contention"
 87: kernel lock contention analysis test                            : Ok
root@x1:~# perf test "lock contention"
 87: kernel lock contention analysis test                            : Ok
root@x1:~# time perf test "lock contention"
 87: kernel lock contention analysis test                            : Ok

real	0m9.143s
user	0m5.201s
sys	0m4.812s
root@x1:~#

Moving to the first patch in this series:

⬢[acme@toolbox perf-tools-next]$ git log --oneline -2
47692286dd856469 (HEAD) perf dsos: Switch backing storage to array from rbtree/list
8c618b58c89ce4c2 (perf-tools-next.korg/perf-tools-next, acme.korg/perf-tools-next) perf test: Reintroduce -p/--parallel and make -S/--sequential the default
⬢[acme@toolbox perf-tools-next]$ alias m
alias m='rm -rf ~/libexec/perf-core/ ; make -k CORESIGHT=1 O=/tmp/build/$(basename $PWD)/ -C tools/perf install-bin && perf test pythond'
⬢[acme@toolbox perf-tools-next]$ rm -rf /tmp/build/$(basename $PWD)/ ; mkdir -p /tmp/build/$(basename $PWD)/ ; m
<SNIP>

root@x1:~# perf -v
perf version 6.9.rc5.g47692286dd85
root@x1:~# perf test "lock contention"
 87: kernel lock contention analysis test                            : FAILED!
root@x1:~# perf test "lock contention"
 87: kernel lock contention analysis test                            : FAILED!
root@x1:~# perf test "lock contention"
 87: kernel lock contention analysis test                            : FAILED!
root@x1:~# perf test "lock contention"
 87: kernel lock contention analysis test                            : FAILED!
root@x1:~# perf test -vvv "lock contention"
 87: kernel lock contention analysis test:
--- start ---
test child forked, pid 2279518
Testing perf lock record and perf lock contention
[Fail] Recorded result count is not 1: 2
---- end(-1) ----
 87: kernel lock contention analysis test                            : FAILED!
root@x1:~#

This breaks bisectability, but then lets see if at the end of the series
it works:

⬢[acme@toolbox perf-tools-next]$ git log --oneline -8
fb401385575211e6 (HEAD -> perf-tools-next) perf dso: Use container_of to avoid a pointer in 'struct dso_data'
0fe118d129ab1c77 perf dso: Reference counting related fixes
35e44adf6103a407 perf dso: Add reference count checking and accessor functions
35673675ebbbac5d perf dsos: Switch hand code to bsearch()
654d60f2f5c737cd perf dsos: Remove __dsos__findnew_link_by_longname_id()
94b0ba802e090b66 perf dsos: Remove __dsos__addnew()
47692286dd856469 perf dsos: Switch backing storage to array from rbtree/list
8c618b58c89ce4c2 (perf-tools-next.korg/perf-tools-next, acme.korg/perf-tools-next) perf test: Reintroduce -p/--parallel and make -S/--sequential the default
⬢[acme@toolbox perf-tools-next]$ rm -rf /tmp/build/$(basename $PWD)/ ; mkdir -p /tmp/build/$(basename $PWD)/ ; m

root@x1:~# perf -v
perf version 6.9.rc5.gfb4013855752
root@x1:~# perf test "lock contention"
 87: kernel lock contention analysis test                            : FAILED!
root@x1:~# perf test "lock contention"
 87: kernel lock contention analysis test                            : FAILED!
root@x1:~# perf test "lock contention"
 87: kernel lock contention analysis test                            : FAILED!
root@x1:~# perf test "lock contention"
 87: kernel lock contention analysis test                            : FAILED!
root@x1:~# perf test -vvv "lock contention"
 87: kernel lock contention analysis test:
--- start ---
test child forked, pid 2289060
Testing perf lock record and perf lock contention
Testing perf lock contention --use-bpf
Testing perf lock record and perf lock contention at the same time
[Fail] Recorded result count is not 1: 2
---- end(-1) ----
 87: kernel lock contention analysis test                            : FAILED!
root@x1:~#

⬢[acme@toolbox perf-tools-next]$ gcc --version | head -1
gcc (GCC) 13.2.1 20240316 (Red Hat 13.2.1-7)
⬢[acme@toolbox perf-tools-next]$ rpm -q gcc
gcc-13.2.1-7.fc39.x86_64
⬢[acme@toolbox perf-tools-next]$

root@x1:~# grep -m1 'model name' /proc/cpuinfo 
model name	: 13th Gen Intel(R) Core(TM) i7-1365U
root@x1:~# free
               total        used        free      shared  buff/cache   available
Mem:        32507912     9081644     3531432     1987616    22554868    23426268
Swap:        8388604      314112     8074492
root@x1:~#

- Arnaldo