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 18D87A5C for ; Tue, 12 Sep 2023 01:43:10 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E6DFFC116A1; Tue, 12 Sep 2023 01:43:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1694482990; bh=MZfgo6MURz3BgruLFMBLXwS/8zrB+gqE+MzIheFwuyE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Q9uNrRTYqaajPGhKYGdTDqSCvE+I3yEoL60HbVUdoQoEJ7vzKYfmNUP53+Mypx2q1 8OIwfqagUNN5TnPbd5zsQPJLoSvgv5bdmvWmyzpcegmaus2km+4OdqGibOxNLDgy5t k4RdZ78uKAfS++llOiKcM3aTM9rEajLrrCs7gXmwPg+j71glXOaXNbtJWPF87eym0b apqMKxjA67c24htXl1O76cWLhuaGPlRSk5sC7FsSVFbEupM5cwJOtiNnXoQqRqgB13 NO903WTV7hKDNuhOb1PEAzexCl5j0DEkNDlXmS5f3K9yBmLmp3PAEtWy9bIj+Jm4cB 9qAACSsgygBxQ== From: SeongJae Park To: Steven Rostedt Cc: SeongJae Park , Andrew Morton , damon@lists.linux.dev, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] mm/damon/core: add a tracepoint for damos apply target regions Date: Tue, 12 Sep 2023 01:43:08 +0000 Message-Id: <20230912014308.38298-1-sj@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230911165144.5002a0ac@gandalf.local.home> References: Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Mon, 11 Sep 2023 16:51:44 -0400 Steven Rostedt wrote: > On Mon, 11 Sep 2023 20:36:42 +0000 > SeongJae Park wrote: > > > > Then tracing is fully enabled here, and now we enter: > > > > > > if (trace_damos_before_apply_enabled()) { > > > trace_damos_before_apply(cidx, sidx, tidx, r, > > > damon_nr_regions(t)); > > > } > > > > > > Now the trace event is hit with sidx and tidx zero when they should not be. > > > This could confuse you when looking at the report. > > > > Thank you so much for enlightening me with this kind explanation, Steve! And > > this all make sense. I will follow your suggestion in the next spin. > > > > > > > > What I suggested was to initialize sidx to zero, > > > > Nit. Initialize to not zero but -1, right? > > Yeah, but I was also thinking of the reset of it too :-p > > sidx = -1; > > if (trace_damos_before_apply_enabled()) { > sidx = 0; Thank you for clarifying, Steve :) Nevertheless, since the variable is unsigned int, I would need to use UINT_MAX instead. To make the code easier to understand, I'd prefer to add a third parameter, as you suggested as another option at the original reply, like below: --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -997,6 +997,7 @@ static void damos_apply_scheme(struct damon_ctx *c, struct damon_target *t, unsigned int sidx = 0; struct damon_target *titer; /* targets iterator */ unsigned int tidx = 0; + bool do_trace = false; /* get indices for trace_damos_before_apply() */ if (trace_damos_before_apply_enabled()) { @@ -1010,6 +1011,7 @@ static void damos_apply_scheme(struct damon_ctx *c, struct damon_target *t, break; tidx++; } + do_trace = true; } if (c->ops.apply_scheme) { @@ -1036,7 +1038,7 @@ static void damos_apply_scheme(struct damon_ctx *c, struct damon_target *t, err = c->callback.before_damos_apply(c, t, r, s); if (!err) { trace_damos_before_apply(cidx, sidx, tidx, r, - damon_nr_regions(t)); + damon_nr_regions(t), do_trace); sz_applied = c->ops.apply_scheme(c, t, r, s); } ktime_get_coarse_ts64(&end); Thanks, SJ > > -- Steve > > > > > > > set it in the first trace_*_enabled() check, and ignore calling the > > > tracepoint if it's not >= 0. > > >