From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 6819314A4FF for ; Tue, 23 Jul 2024 09:36:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721727418; cv=none; b=Vq6ZvGe05cHsRJqBS8NfiTl2mm4lz7BKpRQT3QKEEtWU3yS5bq6ae/ASu3FXhCe+09xAMfjagRhkyIx9j8ES+ppXriCm3BCdG4sm2xBlKuv2D8YO2Egnd80uK24IyB1jXh02Xak/4iAk3bTD55F8eCurFw2B8I20oroxD+t4zzE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721727418; c=relaxed/simple; bh=CYHMWuvUrjnjTEoDZcFER9mdAunDHA3CfsYytFrG75s=; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References: MIME-Version:Content-Type; b=frw4zza52xWMpViLZDHARMhY5FYeSnbZAsF7fkCl4pV0HmBUyXryDt1AJhfY+jpSB5Gq9HnDnzKM3sVa3rj+Ecte6lJY6DzhF8/ZJ0vN6cAW2BMwzJ+05kMcuQZ4/f/e8uEwVvG89MZaqX9AY/3c89OC7tOg6Eo/q3SpPOR+OW4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=MTKBU8R9; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="MTKBU8R9" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1721727415; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=D4sZ7wUuL2xus0RB9yRdz849dpe58TVdYuIJ0fQ3jW4=; b=MTKBU8R9NCGzbvHZTax+DkuncvILTAfSb85E31uQAhJNZvMfVkvJO1+M/dbSvPpqaHE1M7 R78mv/I77TUah0PByC0apgnwoyA4aAsLblz5EKvLFOCf6QRCoZ0mBp+otR6k2xxqYkenyd BWIsDMiI1R0pUyMFl2ztdvt7Mb9sUaI= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-635-Vid7WdEhMjSoTfbD-nTlPw-1; Tue, 23 Jul 2024 05:36:46 -0400 X-MC-Unique: Vid7WdEhMjSoTfbD-nTlPw-1 Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 176101955D47; Tue, 23 Jul 2024 09:36:45 +0000 (UTC) Received: from Diego (unknown [10.39.208.41]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 536B11955D45; Tue, 23 Jul 2024 09:36:41 +0000 (UTC) Date: Tue, 23 Jul 2024 11:36:38 +0200 (CEST) From: Michael Petlan X-X-Sender: Michael@Diego To: Namhyung Kim cc: acme@redhat.com, vmolnaro@redhat.com, linux-perf-users@vger.kernel.org Subject: Re: perf test fail :: "perf stat --bpf-counters --for-each-cgroup test" In-Reply-To: Message-ID: References: User-Agent: Alpine 2.20 (LRH 67 2015-01-07) Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/mixed; BOUNDARY="-1463784192-1159411632-1721727404=:11376" X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. ---1463784192-1159411632-1721727404=:11376 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT On Fri, 19 Jul 2024, Namhyung Kim wrote: > Hello, > > On Fri, Jul 19, 2024 at 2:50 AM Michael Petlan wrote: > > > > Hello Namhyung, > > > > we were investigating some test failures of the testcase mentioned > > in $subj. We have narrowed it down to: > > > > # perf stat -C 0,1 --for-each-cgroup system.slice,user.slice -e cycles -- taskset -c 1 perf test -w thloop > > > > Performance counter stats for 'CPU(s) 0,1': > > cycles system.slice > > 3,020,401,084 cycles user.slice > > > > 1.009787097 seconds time elapsed > > > > As seen, the system.slice is not counted properly in our case. It > > happens even without bpf-counters being involved. > > > > There were rumours that it might be caused due to too small system > > load, but it apparently happens even when the load was replaced by > > "thloop" workload from perf-test's workload library. However, even > > so, if the load was insufficient, we'd see a value – 0 instead of > > "not counted". The "" result is printed if the counter > > wasn't properly enabled and running. > > > > Have you encountered this problem? What could cause it? > > Sometimes, it depends on the system activity. > I assumed there would be some system operation running > on the given CPUs at any time. If not, it can fail.. Thanks for response. However, in such case, I'd expect "0" value instead of "". As far as I understand, "" occurs when an event cannot be even opened, "" appears when the event can be opened, but for example there aren't enough free hardware counters, so it does not run any counting actually. But for cases when there is not enough load, we get simply low numerical values, or 0, don't we... Michael > > Thanks, > Namhyung > > ---1463784192-1159411632-1721727404=:11376--