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Mon, 10 Aug 2026 16:17:27 -0700 (PDT) From: Kayra Cizmeci To: vineethr@linux.ibm.com Cc: bsegall@google.com, dietmar.eggemann@arm.com, juri.lelli@redhat.com, kayracizmeci@gmail.com, kprateek.nayak@amd.com, linux-kernel@vger.kernel.org, mgorman@suse.de, mingo@redhat.com, peterz@infradead.org, rostedt@goodmis.org, sh@gentwo.org, vincent.guittot@linaro.org, vschneid@redhat.com Subject: Re: [PATCH] sched/fair: Let sync wakeups target the waker's core Date: Tue, 11 Aug 2026 02:17:24 +0300 Message-ID: <20260810231724.65791-1-kayracizmeci@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi Vineeth, I tested the things you wanted on the same box as before in the current baseline (d58772d8520c) and baseline + patch. command: perf bench sched pipe baseline: run 1: usecs/op: 1.435285, ops/sec: 696725 run 2: usecs/op: 1.305019, ops/sec: 765685 run 3: usecs/op: 1.143834, ops/sec: 874176 run 4: usecs/op: 1.549996, ops/sec: 645162 run 5: usecs/op: 1.136511, ops/sec: 879885 baseline + patch: run 1: usecs/op: 1.362729, ops/sec: 733821 run 2: usecs/op: 1.420710, ops/sec: 703873 run 3: usecs/op: 1.229553, ops/sec: 813303 run 4: usecs/op: 1.453649, ops/sec: 687923 run 5: usecs/op: 1.204788, ops/sec: 839921 I don't think these numbers really mean anything. Range is too big, as an example, on baseline the biggest usecs/op is 1.54996, while the smallest one is 1.136511. And this pattern just repeats itself. The range is smaller on the baseline + patch, but I don't really know what it means. command: perf stat -r 10 -e cycles,cache-misses,L1-dcache-loads,L1-dcache-load-misses,cpu/event=0x64,umask=0x08/ perf bench sched pipe I got the L1-dcache-load-misses and L1-dcache-loads from the perf list, as for the other one I got it from tools/perf/pmu-events/arch/x86/amdzen3/recommended.json, l2_cache_misses_from_dc_misses. I ran this once on both the baseline and baseline + patch since it runs 10 times with -r. baseline: cycles: 12317680674 cache-misses: 19567069 L1-dcache-loads: 2792471451 L1-dcache-load-misses: 52924092 L2(event = 0x64, umask = 0x08): 18696435 baseline + patch: cycles: 12304183071 cache-misses: 20105690 L1-dcache-loads: 2796772374 L1-dcache-load-misses: 50928594 L2(event = 0x64, umask = 0x08): 18928237 In the old test, the cycles decreased 1.40%, but in this one the cycles decreased 0.11%. Also cache-misses increased 4.60% in the old test, but in this one it increased 2.75%. I think this may be because the baseline is different, but that is just a guess. I also tested LLC, or L3, same as L2 I got the values from /amdzen3/recommended.json, l3_misses. baseline: L3(event=0x04, umask=0x01): 23064400 baseline + patch: L3(event=0x04, umask=0x01): 22870280 L1-dcache-load-misses went down 3.77% while L2 went up 1.24% and L3 went down 0.84%. Also please drop the Tested-by, I'll retest on v2 and send a new one. Thanks, Kayra