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 2DFD4CD37AC for ; Thu, 14 May 2026 00:07:04 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 53DAE6B0088; Wed, 13 May 2026 20:07:03 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4C7076B008A; Wed, 13 May 2026 20:07:03 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 38EA56B008C; Wed, 13 May 2026 20:07:03 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 236C56B0088 for ; Wed, 13 May 2026 20:07:03 -0400 (EDT) Received: from smtpin02.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay09.hostedemail.com (Postfix) with ESMTP id A40928CA40 for ; Thu, 14 May 2026 00:07:02 +0000 (UTC) X-FDA: 84764085084.02.6A918A3 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf16.hostedemail.com (Postfix) with ESMTP id DD5D3180009 for ; Thu, 14 May 2026 00:07:00 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=oBq66Qra; spf=pass (imf16.hostedemail.com: domain of sj@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=sj@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1778717221; 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=AEkq/eGfgOVH7wzNRnWx9Om54LYBeTY9WfyooVWWtCc=; b=qXQzPyZ/W728OBuruhsXSk8nadi+GQw4aeq7dqAz/881ygLd4sdbjnVf8HlwHXaOd8VXe9 zlzP+UKiHHrCsfriOGYUCw7rjIxLJPcGElyw/EffIieqOy9dSQoy+3KZQvzOnnwrUBmH11 EhJgRT/Ulmfqzehh5EF9J4J3I2ZDIO8= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=oBq66Qra; spf=pass (imf16.hostedemail.com: domain of sj@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=sj@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1778717221; a=rsa-sha256; cv=none; b=oiIZQlNjG2gmHdzKIxaNMOtoBBGhdkamMWc5B4y799SViAX911nA28JkiqE3YJSaisia2K WmwvrZBvc3pz5mmwQAptjeGhCTC9HOuO4wRVAtCWYEEwTOvz0e46zNLMVWePF5knvpZ8sv zn3SYJ9kwhmlI956bu8gHbSs8Mzdmu8= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id C598E40DDF; Thu, 14 May 2026 00:06:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F26F3C19425; Thu, 14 May 2026 00:06:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778717219; bh=DWVNCpyyXtijugIs1t5TkZJG/znt8BoX/RA4gIbC7nk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oBq66QraZzrbe5XdmdxhQXuV+x3xo87BOW5PwtTKnsZF5cZjBT0Dd0aFJPNxPc91s HnbIdR4iAlzocR04Pr3jLgM58xMltMZP+RpCHN6PbkgGrH3sXkzeZ/yu3c6RRYXV9E 4o3PzZ/ctIr4yvs8dr2G+6YBOQ71cpUX3lJyvtyvl7Dk07z1t1wvXMk+85sdOYnATN 0u1pFzfC3HsWEpEY7yWC/DgtPoXPcPdqunQznk4hbuKEFPY9oMPlvLJx8d53BxuNWk G2gyml0sZhOVP430eoyy6YawFbmTOlLMVd15w+pDwZjS80uK1tcHexVqpkFVpqasbr BE9FwtRXq4R1w== From: SeongJae Park To: Steven Rostedt Cc: SeongJae Park , Andrew Morton , Masami Hiramatsu , Mathieu Desnoyers , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org Subject: Re: [RFC PATCH v2 18/28] mm/damon: trace probe_hits Date: Wed, 13 May 2026 17:06:10 -0700 Message-ID: <20260514000611.147809-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260513140732.2320c563@gandalf.local.home> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: DD5D3180009 X-Rspam-User: X-Stat-Signature: ase7rkk8m475ywz3waju6x46oig8x4fz X-HE-Tag: 1778717220-30029 X-HE-Meta: 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 +NAHttJD sdSCyTc+08vDNcesmiqsEjnDWPOM6GobUQKFiRfVl3raLONZrf5aGQLr48ai2Ajyaotwp4Xlpf5Ea4HmVbn/BYAni2hu+OZkWHyBYGe33nICF4lAaU6Fg2Js17q7BLoSk03ed0Labolh9HrmN+EztAwmxYIjGCa4qiTzof8xTJOEHkK60FAOd2FXg5oaYuI3r2W0EXiH7Zj1KbXVrXi+zSwL4gIMrg3vi7E5bepqmhMDSIqxIfwHg+YncLxPsyxMb2f+GQb5g8WXz+9+N3a0aDnRUdAOzgvhOkuXUs06ODC0qRjVnxOEsVJyQOKBdsEYTVXxnGDcIkL+yRsFHxo8OpzzYcw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 13 May 2026 14:07:32 -0400 Steven Rostedt wrote: > On Tue, 12 May 2026 07:36:33 -0700 > SeongJae Park wrote: > > > Introduce a new tracepoint for exposing the per-region per-probe > > positive sample count via tracefs. > > > > Signed-off-by: SeongJae Park > > --- > > include/trace/events/damon.h | 36 ++++++++++++++++++++++++++++++++++++ > > mm/damon/core.c | 7 +++++++ > > 2 files changed, 43 insertions(+) > > > > diff --git a/include/trace/events/damon.h b/include/trace/events/damon.h > > index 7e25f4469b81b..d7b94c7640217 100644 > > --- a/include/trace/events/damon.h > > +++ b/include/trace/events/damon.h > > @@ -130,6 +130,42 @@ TRACE_EVENT(damon_monitor_intervals_tune, > > TP_printk("sample_us=%lu", __entry->sample_us) > > ); > > > > +TRACE_EVENT(damon_aggregated_v2, > > + > > + TP_PROTO(unsigned int target_id, struct damon_region *r, > > + unsigned int nr_regions, unsigned int nr_probes), > > + > > + TP_ARGS(target_id, r, nr_regions, nr_probes), > > + > > + TP_STRUCT__entry( > > + __field(unsigned long, target_id) > > + __field(unsigned long, start) > > + __field(unsigned long, end) > > + __field(unsigned int, nr_regions) > > + __field(unsigned int, nr_accesses) > > + __field(unsigned int, age) > > + __dynamic_array(unsigned char, probe_hits, nr_probes) > > + ), > > + > > + TP_fast_assign( > > + __entry->target_id = target_id; > > + __entry->start = r->ar.start; > > + __entry->end = r->ar.end; > > + __entry->nr_regions = nr_regions; > > + __entry->nr_accesses = r->nr_accesses; > > + __entry->age = r->age; > > + memcpy(__get_dynamic_array(probe_hits), r->probe_hits, > > + sizeof(*r->probe_hits) * nr_probes); > > + ), > > + > > + TP_printk("target_id=%lu nr_regions=%u %lu-%lu: %u %u probe_hits=%s", > > + __entry->target_id, __entry->nr_regions, > > + __entry->start, __entry->end, > > + __entry->nr_accesses, __entry->age, > > + __print_hex(__get_dynamic_array(probe_hits), > > + __get_dynamic_array_len(probe_hits))) > > +); > > + > > TRACE_EVENT(damon_aggregated, > > > > TP_PROTO(unsigned int target_id, struct damon_region *r, > > diff --git a/mm/damon/core.c b/mm/damon/core.c > > index fe6c789f2cecb..14b15c9876516 100644 > > --- a/mm/damon/core.c > > +++ b/mm/damon/core.c > > @@ -1905,6 +1905,11 @@ static void kdamond_reset_aggregated(struct damon_ctx *c) > > { > > struct damon_target *t; > > unsigned int ti = 0; /* target's index */ > > + unsigned int nr_probes = 0; > > + struct damon_probe *probe; > > + > > + damon_for_each_probe(probe, c) > > + nr_probes++; > > Is the above logic needed when the tracepoint isn't enabled? If not, then you could add: > > if (trace_damon_aggregated_v2_enabled()) { > damon_for_each_probe(probe, c) > nr_probes++; > } > > And change the tracepoint to be a conditional tracepoint: > > TRACE_EVENT_CONDITION(damon_aggregated_v2, > > TP_PROTO(..), > > TP_ARGS(..), > > TP_CONDITION(nr_probes > 0), > > [..] > > And then the tracepoint is only triggered if nr_probes is greater than zero > (to handle races between the tracepoint being enabled in between the above > check and where it triggers). It is not needed when the tracepoint isn't enabled. I will follow your suggestion in the next revision. Thank you for the nice suggestion, Steven! Btw, if you don't mind, may I ask your opinion about the name having '_v2' suffix? I chose that as an RFC phase temporal name that doesn't break the compatibility, planning to give it a better name later. But I start feeling just extending the original one might be another option because tracepoints are not strict stable ABI to my understanding, and the change of the TP_prink format should be simple enough (append the probe_hits= part) that the user space could reasonably deal with. Thanks, SJ [...]