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[213.44.135.146]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3c077c57aa0sm2801982f8f.66.2025.08.19.01.52.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Aug 2025 01:52:19 -0700 (PDT) From: Valentin Schneider To: Srikar Dronamraju , Yury Norov Cc: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , linux-kernel@vger.kernel.org Subject: Re: [PATCH] sched: simplify sched_init_numa() In-Reply-To: References: <20250719210753.401129-1-yury.norov@gmail.com> Date: Tue, 19 Aug 2025 10:52:19 +0200 Message-ID: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On 21/07/25 14:02, Srikar Dronamraju wrote: > * Yury Norov [2025-07-19 17:07:51]: > >> From: Yury Norov (NVIDIA) >> >> The function opencodes for_each_set_bit() macro. >> >> Signed-off-by: Yury Norov (NVIDIA) >> --- >> kernel/sched/topology.c | 7 +++---- >> 1 file changed, 3 insertions(+), 4 deletions(-) >> >> diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c >> index b958fe48e020..7dc3c79aa480 100644 >> --- a/kernel/sched/topology.c >> +++ b/kernel/sched/topology.c >> @@ -1932,10 +1932,9 @@ void sched_init_numa(int offline_node) >> return; >> } >> >> - for (i = 0, j = 0; i < nr_levels; i++, j++) { >> - j = find_next_bit(distance_map, NR_DISTANCE_VALUES, j); >> - distances[i] = j; >> - } >> + for_each_set_bit(j, distance_map, NR_DISTANCE_VALUES) >> + distances[i++] = j; >> + > > Dont we need to reset the value of i; > That. > Also now we may be iterating for NR_DISTANCE_VALUES instead of nr_levels. > It should be okay, since NR_DISTANCE_VALUES is just 8. > DISTANCE_BITS is 8, NR_DISTANCE_VALUES is 1 << 8 aka 256. But here the use of for_each_set_bit() means we'll get just one extra iteration compared to using `nr_levels`. That said, since we *have* to compute `nr_levels` to allocate sched_domains_numa_distance, IMO we're not gaining much by using for_each_set_bit() here. >> rcu_assign_pointer(sched_domains_numa_distance, distances); >> >> bitmap_free(distance_map); >> -- >> 2.43.0 >> > > -- > Thanks and Regards > Srikar Dronamraju