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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: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 18F4D140014 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: 1yp4ju4jsf7d5cofkywhnffqq436ph8m X-HE-Tag: 1694482991-4861 X-HE-Meta: U2FsdGVkX1827WGv/VFav6VrJ5jpaeA+ic8aDsWy+tzwk+m2HJ47UfUH9DjAKDpOVbfoqxkcPtvb5WSWQKrDShCjJNWCmstvkgpnfBRp+AszrwvoK2fAYtq8Dx9DrfLbeZhkoJcESMxIJHeqyXBp9RqCcCCbH55knTUIZzywcG9aAAV6Qz9mEXOdj1QYwnqLq2qKrcKnM08XKz6bGN1IZkGq+h+VzioO39nnc3/a17TY61iAwnrsDokYg4qdvbj24V0r5n/hqEcQhL1YFuihTZSVSEFAo9v4fmTgx+HFEGICpRxlZZugJPEIkS/gLUs2OBJ50NuJ+3djRCONiEfj8KYdm/srL7UvP/xI0rV4vOTteym6zte9ggO/r3sQZvYjwl1AainTEfEybfLpsFr9IcDXbKbGPyk7n8jTKW7dvfzkhbpxHWvSMAp+bbimYeUhQesuj2JqtHpt0IzrlQRHIdfdTS6kPUZdomgjeIJehZGvsdhAnkgJZ70DAUyUuU/BoXW52fQBiooFdEiSaapXjJvdKJ/26yrnCl96Jqtverrjv3nxjlfdyWFEmEHK0iyE1xmzmpd8ieqnsu8GP6tp84C4TNKtIXiWtgRr3/c0qCeLdaM3Du/ttpehyyd9lVtznRttXsikIgAOWk5ie9+9xn2Sx0L9jX24qgDM/ZkPHOmzpAUdKXr4DIXkQr68B4MwBc907mrN66k7eWrlKSoIDbbCLStJrhA3YZQv6s1ubbWTSdvG4yWSH5JjVBpUKrYT5sNfqxmmvtL1yDOv83qKpwZ//vVQvmrhiYC45Ae3Q1U5xA/U15vs4ajDzRdcyH+vFALGR9DIkKUabmTy+5+hOrUZR7xk6aUPvZGTaxwZLffT3pII5eaMXelH+J8Lz0Mzlo+mff/78hRHmAUhFnEeMmWI4hPrTDF6ra2BpXlw6O3jPpDK9u6fpQE04LQCwdhMvKofF/j+KLEXQkyu0DH CUv8uu2R 3LVLfxgaRe8pVy3iudnPqV/978IKZZCjzwidoHtpEgfqGj8FUIDS6nwJgtGVIhN4XJ8AQj4UZcZV2BHniVzFbpkr2DKZ8CHI68b6/hm9e2KnShDYYHMcuKkZbFw48bvoQCR0VWRN9W517xEzFwvPEj04R9i28T3K1UKYN3FjtLEQQANTwY40et6YnjcI1LiKRQa/1a8wx9t/Ur+eKaofGh+HQr6qPxMiEtqDcmonBm1CO+/oOqUlDyDWva9tZXq6DFJkCTe2fdv9A6LSNV5pDoZr3lDU+x191rvJdoS7Kepmzf1YIwcWKAgr+ogFXUl9Irp8Qf23H7VH78aAnHgf4JTT+MZQlHWB4LB0OB5oCf0WUF1RkcLt1wcMVCtmORcHPQVQbi8hwtn0rhxU= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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. > > >