From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 5CC353546EB; Sun, 31 May 2026 16:54:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780246487; cv=none; b=In3Es1goAtR0x41C1x81G/WjaEXJcFzAoioXxZDqwhO2CdYKArAGsMILk7RPNtwJ4vrND21tzoFs4grlLRtqAOR2++/REj9B6+6jG5747YOQSVZ0nTCBR2GzVjDlLV9+pR4BJOpOpTJO7335aDpRy+yYQZTByJtZqX9+a5S03Co= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780246487; c=relaxed/simple; bh=whf+LvG8vN5IgqK/zShnfRKq1s31SOdSn8V5EwdZkYk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=RzKiKz0tK14WtVDd+ubjkIu6+xONiWPVrE8WcmgsQOyjbFMAgFthzCUyD5pCIbz0t1+6duVbE4o3aP5ppXI3mRoAZa0Xj8ij+5muQ+9PkpM3nKMHbdgSQZkmb4Vt9I+umeYlXd7oMYQa/vCs3PPus98XWKH1CSTOpZKEyZg0MJw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DHSnVtfW; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DHSnVtfW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9F94E1F00893; Sun, 31 May 2026 16:54:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780246486; bh=DxNfjlt8z6ra/rBSB/w2v0ydMZ2aKkX0YJFO0NVjmRo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=DHSnVtfWrjD47T/hXx9+C2HLPFW1gEiP+3fvg77a646RvPO5OVH/UshZcO60Vwhj/ h2qaXmpCXYhMCwutStXqyrzo2sR6P07O/xM+4oSUr98tT9wGhYcuUBYIsPF9E7RHLB WjgsEOvn/ISIk5GosPPU2wC1nU26GZX3LPyPMnlUMN/IyuBOsOts+iRYN1QM8PrUdY zDwmwDCnrmXWSwdxTrhqEaAGlaaZiNshzM6uPKnHSArATFYJTq3cxgxKFfrFh1r9Jg VWFaqGOuO5g78m/pAxQOOpc29LvEZqGSvJR80sZ8vZmBHvi8kQSnonv1OObpLxq71B r0LUX7qAcoOdQ== From: SeongJae Park To: Kunwu Chan Cc: SeongJae Park , shuah@kernel.org, damon@lists.linux.dev, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Kunwu Chan , Wang Lian , Kunwu Chan Subject: Re: [PATCH 4/5] selftests/damon/damos_tried_regions: handle empty tried regions in early cycles Date: Sun, 31 May 2026 09:54:36 -0700 Message-ID: <20260531165437.99410-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260531091724.84381-4-kunwu.chan@linux.dev> References: Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Sun, 31 May 2026 17:17:23 +0800 Kunwu Chan wrote: > From: Kunwu Chan > > The test aborts if the initial aggregation cycles produce zero > tried regions. This can happen on slow machines, causing false > failures. Skip empty cycles and retry up to 200 times before > giving up. Also check that enough samples were collected before > computing the 50th percentile. I agree this will make the test be more reliable. I'm bit concerned if 200 times retry can make the test run too long, though. Also, could you further elaborate why this can fail on slow machines? That is, DAMON will check the access of 'access_memory_even' process every 5ms. Are you thinking the 5ms is too short for 'access_memory_event' to make the expected access (accessing the 7 regins of 10 MiB size) within? If so, should we increase the sampling interval before retrying? I also suspect if the unreliable results you seen is due to the fact that DAMON is not flushing TLB, like we discussed before. If that's the case, could we increase the working set size of this test, similar to the wss_estimation test? [1] https://lore.kernel.org/20260525144846.604907-1-kunwu.chan@linux.dev Thanks, SJ [...]