From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 46CE2F433CC for ; Thu, 16 Apr 2026 00:22:03 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A29AE6B0005; Wed, 15 Apr 2026 20:22:02 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9D9EC6B0088; Wed, 15 Apr 2026 20:22:02 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8C88B6B008C; Wed, 15 Apr 2026 20:22:02 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 7AFED6B0005 for ; Wed, 15 Apr 2026 20:22:02 -0400 (EDT) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 3D7878C158 for ; Thu, 16 Apr 2026 00:22:02 +0000 (UTC) X-FDA: 84662516484.08.CDDCE5D Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf23.hostedemail.com (Postfix) with ESMTP id 89FFC140005 for ; Thu, 16 Apr 2026 00:22:00 +0000 (UTC) Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=KR7dFtol; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf23.hostedemail.com: domain of sj@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=sj@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1776298920; a=rsa-sha256; cv=none; b=N8KARK/hpxc4CSJ6zpoCHhX602gO+4mNcN22puyDIc3LcEzuACd5HcaUK5+7O+/hYr5/zj l9UEF5Oyl/vItUikJ+iXkxcY0na22j+TlwI4Pg/zyZ6ELYbqz4t8CLOvZGzefih4BJxEIL 1006ZNKPC6VqtTD2DTJHt45MgTdposY= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=KR7dFtol; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf23.hostedemail.com: domain of sj@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=sj@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1776298920; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=sFboVlqhXU7c329R1vpVRGNhfS21/nkba0oenxk99jc=; b=S6qKuLOClfccZyyKJSgpIrPBYCj7DGdxr4ZrwLNmZhauawfffo3SvXKGh1EVzMkBftPoVT mlRf6RsUrEVQGPsFdGnaWgZGsPTCQjZthVU9ZNdd/MQdGQxxdXT16c0CQDrLkwfIdzS20S ENe530dWOxnaSJg++mt2dvcm/VQkA/4= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id AC6D344060; Thu, 16 Apr 2026 00:21:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 67CECC2BCB9; Thu, 16 Apr 2026 00:21:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776298919; bh=oAz4P2Xf/vMXHQmZ0zMlkiiML8XeygCzQMESdno0b8E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KR7dFtolv76LoMS4QdAmmx6dkibmmtpjYB7wsALDytuBX/USmNta5JsKJoX1Xd5Gx XIAzFMC1xwjGPHYLAD7pTRooT2nNizetTkkLtBvgaS4uAybHdZ2+xIE/jOk8QQLvBr HsxCSycHu4YAetBYhg8/w78znAJqPKtQKLS7PFbnJeeAotTFcelLtyA1mKoHAvlIfq XPbcYs/Z1Pm5VC4h9SATiew+LIL1RD1YmtrsoNZ3cvpJWyrfd7cWvm9JzstA6Lch5h 96Dj1htYEw5Kngtaz4DaAlJCLyhC+3mXJl9px/FPxKodCWwTGD/NuuCKtWBhSs1fPK pN6Vk++rTg4Hw== From: SeongJae Park To: Cc: SeongJae Park , Andrew Morton , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH v1.2 1/2] mm/damon/stat: add a parameter for reading kdamond pid Date: Wed, 15 Apr 2026 17:21:46 -0700 Message-ID: <20260416002149.87090-2-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260416002149.87090-1-sj@kernel.org> References: <20260416002149.87090-1-sj@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam10 X-Stat-Signature: e36ozs9ia9n7jdeqbgys4j8w8tqkr3fn X-Rspam-User: X-Rspamd-Queue-Id: 89FFC140005 X-HE-Tag: 1776298920-558079 X-HE-Meta: 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 mmwIqZ23 O8ZRJSCdA89ode1XyfoesnpnEUyr+tGgtralna3SpPHa4sXiAGfZlNcUjlob6d6fJDMcLcxcNrxnwfe1dqbWOR+QV/00UgjVAn0d6xt+Lml31tBfZtpWY7NZWQJPL/APtQHq04MqL16IWcYvPjFQGD+S1cbleidM60qH5TrUnFIkIgBVWSvrg3oJq8whineoUsvzqafX07yElq5ERNUQd8tqX2Nc2+ZgXNhWdWaCXmIEJbzU= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Knowing the pid of the kdamonds can help user-space management including monitoring of DAMON's system resource consumption. To make it easier, DAMON_SYSFS, DAMON_RECLAIM and DAMON_LRU_SORT provide the pid information. DAMON_STAT is not providing it, though. Expose the pid of DAMON_STAT kdamond via a new read-only module parameter, namely kdamond_pid. This also makes DAMON modules usage more standardized, because DAMON_RECLAIM and DAMON_LRU_SORT also provide the information via their read-only parameters of the same name. Signed-off-by: SeongJae Park --- mm/damon/stat.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/mm/damon/stat.c b/mm/damon/stat.c index 99ba346f9e325..4901e9a7c3398 100644 --- a/mm/damon/stat.c +++ b/mm/damon/stat.c @@ -44,6 +44,15 @@ module_param(aggr_interval_us, ulong, 0400); MODULE_PARM_DESC(aggr_interval_us, "Current tuned aggregation interval in microseconds"); +/* + * PID of the DAMON thread + * + * If DAMON_STAT is enabled, this becomes the PID of the worker thread. + * Else, -1. + */ +static int kdamond_pid __read_mostly = -1; +module_param(kdamond_pid, int, 0400); + static struct damon_ctx *damon_stat_context; static unsigned long damon_stat_last_refresh_jiffies; @@ -260,6 +269,14 @@ static int damon_stat_start(void) damon_stat_context = NULL; return err; } + kdamond_pid = damon_kdamond_pid(damon_stat_context); + if (kdamond_pid < 0) { + err = kdamond_pid; + kdamond_pid = -1; + damon_destroy_ctx(damon_stat_context); + damon_stat_context = NULL; + return err; + } damon_stat_last_refresh_jiffies = jiffies; call_control.data = damon_stat_context; @@ -269,6 +286,7 @@ static int damon_stat_start(void) static void damon_stat_stop(void) { damon_stop(&damon_stat_context, 1); + kdamond_pid = -1; damon_destroy_ctx(damon_stat_context); damon_stat_context = NULL; } -- 2.47.3