From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9166C1ABEBA; Mon, 4 Nov 2024 23:34:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730763281; cv=none; b=sXLZX/0FPl8O/YjElJiXz2JIe+SIium/TIzrp692EqWeDYgkaMJEMgAcNmgqPsPYYA65SDgTy+rqcTPc7o6dJGGh2rVYz3SFJ5pCGFPPXribnT5zzlSsbP5uI0oQfcboFHyfFoeDBZFXCwLyUM5Gj5VSycCETbn2eJw//YdVVKQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730763281; c=relaxed/simple; bh=88TYumyhWbfjVMyfSLi2/8DI4JnQwU62uhhbbbI3EPc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Yj9tANpXxwYx0kslX3PhSF7smrVsE4agwDFo9q13yIgEK6PCG86KQtF0gA9i9OyCG/6EMSBr6M423cmhTAGJJ30+o1sS4O6d66rVm2/4XOGsvMqJd+tctCRzm+QiQ1opYxzElNKdXKjw3CPW3/46KAnF4oNu4EETEmdY04FpjkI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bk2WE9bR; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bk2WE9bR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C5FDCC4CED1; Mon, 4 Nov 2024 23:34:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730763280; bh=88TYumyhWbfjVMyfSLi2/8DI4JnQwU62uhhbbbI3EPc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=bk2WE9bRtabX0pG/dgRccsTHBgk3EKcHrehNbj5h74YnMHZlwsGo6fKaH2m0wXp3k iE6KH+DZpT5uYmvB2VIz1m03obmFmHmkhfyYiwZ9rYD07lTh4eW+BFFwppXdOKnxLt 5AnTsWLqxlW1sjxaiQ8JU638m/VdU11GB5DrKh6pj3QWgeZrDKj7zTtosRmTxpy0Fy RIIeVGYc3DP2GIRJ5xeOZKGa0f8VmGlLKgwWlLZIuOCYhlTNFUbX1WimsV/6oNZ/r+ MdytaQ1+UQix5E25D6/Hi6ryDchy3Fwhno1axOeFEVqRn2b4Iho2RoLkO1OSUKNbe4 uWTSuW+7cv2jw== Date: Mon, 4 Nov 2024 15:34:38 -0800 From: Namhyung Kim To: Ian Rogers Cc: Arnaldo Carvalho de Melo , Kan Liang , Jiri Olsa , Adrian Hunter , Peter Zijlstra , Ingo Molnar , LKML , linux-perf-users@vger.kernel.org Subject: Re: [PATCH] perf test: Fix LBR test by adding indirect calls Message-ID: References: <20241103002414.2281869-1-namhyung@kernel.org> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Sat, Nov 02, 2024 at 09:58:03PM -0700, Ian Rogers wrote: > On Sat, Nov 2, 2024 at 5:24 PM Namhyung Kim wrote: > > > > I've noticed sometimes perf record LBR tests failed on indirect call > > test because it has empty branch stacks more than expected. > > > > The test workload (thloop) spawns a thread and calls a loop function for > > 1 second both from the main thread and the new thread. However neither > > of them has indirect calls in the body so it ended up with empty branch > > stacks. > > > > LBR any indirect call test > > [ perf record: Woken up 21 times to write data ] > > [ perf record: Captured and wrote 5.607 MB /tmp/__perf_test.perf.data.pujKd (7924 samples) ] > > LBR any indirect call test: 7924 samples > > LBR any indirect call test [Failed empty br stack ratio exceed 2%: 3%] > > > > Refactor the test workload to call the test_loop() both directly and > > indirectly. Now expectation of indirect call is 50% but let's add some > > margin for startup and finish routines. > > > > Signed-off-by: Namhyung Kim > > --- > > tools/perf/tests/shell/record_lbr.sh | 2 +- > > tools/perf/tests/workloads/thloop.c | 9 ++++++--- > > 2 files changed, 7 insertions(+), 4 deletions(-) > > > > diff --git a/tools/perf/tests/shell/record_lbr.sh b/tools/perf/tests/shell/record_lbr.sh > > index 8d750ee631f877fd..7a23b2095be8acba 100755 > > --- a/tools/perf/tests/shell/record_lbr.sh > > +++ b/tools/perf/tests/shell/record_lbr.sh > > @@ -121,7 +121,7 @@ lbr_test "-j any_ret" "any ret" 2 > > lbr_test "-j ind_call" "any indirect call" 2 > > lbr_test "-j ind_jmp" "any indirect jump" 100 > > lbr_test "-j call" "direct calls" 2 > > -lbr_test "-j ind_call,u" "any indirect user call" 100 > > +lbr_test "-j ind_call,u" "any indirect user call" 52 > > lbr_test "-a -b" "system wide any branch" 2 > > lbr_test "-a -j any_call" "system wide any call" 2 > > > > diff --git a/tools/perf/tests/workloads/thloop.c b/tools/perf/tests/workloads/thloop.c > > index 457b29f91c3ee277..fa5547939882cf6c 100644 > > --- a/tools/perf/tests/workloads/thloop.c > > +++ b/tools/perf/tests/workloads/thloop.c > > @@ -18,14 +18,16 @@ static void sighandler(int sig __maybe_unused) > > > > noinline void test_loop(void) > > { > > - while (!done); > > + for (volatile int i = 0; i < 10000; i++) > > I don't think the volatile here will stop a sufficiently eager > optimizing compiler. I think it may need to be static as well. Ok, probably we can disbale optimizations in this code like others in the test workloads. Thanks for your review! Namhyung