From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ed1-f97.google.com (mail-ed1-f97.google.com [209.85.208.97]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 86C295AA67B for ; Thu, 17 Sep 2026 16:25:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.97 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789662338; cv=none; b=bcmxhn2qOlVGVuFEW5HgyYJ9LWiXy6H7oD24UeC+HaVNDmofjns3RM4OTLHlHKqPLr4GB1Z19DVBLdzCxm1pMDBc64F+5pQRxsLkLgD5LScpuPoymYjozPwn6623EOyjtV75x6A7kwPrZcEZCYkgoM7OM713mtEf2KXn68G2z/c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789662338; c=relaxed/simple; bh=rtvmHSWXSmxkuH2d1GtpV9D/iH6hOVoLVjJ/X0LT4VU=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=kaCDiQIznXIoHGr+bJzQ1GDb7Y8UBblgY9XJE+GPgSrGcn88Hux/r9e8zJ4u0obsPij6aDYz6jLciU2Gxb3uglw4+hhBon7T3QfgLq5W/oDlbjnsTd0N1IX/rgo4ZhGlX++VHPOi47CDMF0mfw7lTjROkySHjFtP4NYPWOeBODA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=everpuredata.com; spf=pass smtp.mailfrom=everpuredata.com; dkim=pass (2048-bit key) header.d=everpuredata.com header.i=@everpuredata.com header.b=rc2gdHiX; arc=none smtp.client-ip=209.85.208.97 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=everpuredata.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=everpuredata.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=everpuredata.com header.i=@everpuredata.com header.b="rc2gdHiX" Received: by mail-ed1-f97.google.com with SMTP id 4fb4d7f45d1cf-6a9bd4db6ccso346800a12.0 for ; Thu, 17 Sep 2026 09:25:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=everpuredata.com; s=google; t=1789662335; x=1790267135; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=cI+xjeNHVNst3t+SGlRsF85lt+goiabsbiUNU03nAKw=; b=rc2gdHiXG4kPrPnZgypirmqXT1nL4csf38j8bCQRkSOXcFYvWHfcmvpsfwvpE0TvAu eSiyLspLJKF8dPj1SLT+SPQHqqUmRYthPb5aVVo3bCr3PSR4foQbbCuCdzryl3AhDluW uDziRHpEWKlm3yIGJfHd4YvA4fMjvk8rSJnNe68lUxo8fNQBhVeMet0vD83DxU1dPNMF tfX2wDujjO5CDwd5uEH5aq3BklBmPh1v+c0ormFfRhN65hIDjbkiLPZMnxt1rOpsPW0R DRNUNL7buAGH+XTD/nO88Jvk61QwIa+TFTvgcjbBRkOWVs+V8veoNLr3LodiV97m8O2F harA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1789662335; x=1790267135; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=cI+xjeNHVNst3t+SGlRsF85lt+goiabsbiUNU03nAKw=; b=K1FIHdyiAUZVHI9UN18uiSuvOZ7HMI7h6ZJJ6gQk5/6FSVjjPdXU9e9pkKvxBNRKRY TPZbhKuolW3K0yHcQeB9cDjZ3+55oJuovu1XOR4jrolPAgNLRh2kWRMB/3FamJagCE48 TyJdUgNuAnzCk+DNwktW94BUkIMQFW5VNoyblEvgdLaahQSaAeYC3RPkSqwIlHtbWu0n IwinLDg+MZpVkc6iMu8QDuhmlgcaN3BYJsLIZnZN8GHJJbyizxJKi1E9pzxzLU58Rll8 RrWaqiMb+gG+6eHUqMX6HR6ffYxFeoHla/ajbOCdZMmwo4OsszpJHSsan7H2TZb2vfC2 NXwQ== X-Forwarded-Encrypted: i=1; AKwUvBxOefRNl/PqgNU5DbHO6W90STxyzKaxjK7OyLoZjfi1e9ZcbeLPykjGilREXbyzxf93Huwo1HPrXK1a/rM=@vger.kernel.org X-Gm-Message-State: AFuF++kGnKoMjWqU1OdOK7d+dJh3ZZ8rcjLZMxUzBktJEADAEOqenaqR 4ZinHx6b5qXCVEbvvhC6NdtRQRjDkE9Zw0zdLJX249ZypJZknaNMH2YCf3VRlYLX4ACMejZuI5H cJefVn0mD1XUx66fkOSxFWdCki+af5XC6qE6+ X-Gm-Gg: AYBFou1FsRsX/4xx1k4r5BVtUxjN+CXmKQdFIL84hz6gfrtRXG9B8fy94c2eqOt8tUI T7a0ptynWzAsJkAdLHvYG9IGLHsFm9y0ip1ZxFXSrw6vLW+1U+UppAtGOmfEw9C9tKKlVMBJ+4f qIvA7W5OuV0tQvlMtoGGSroZoXwXF4TK58DfzC3m67kZSvaPSxPNgtXwBjGluSqYPEl71Of1KCr LVT7OKvyrYA7HYpYjGkcgwvD0y1AVoQTZQkLnWIQ2MI/99jGdCPwcnx88PB4UG4gkVswgOpWvYi nHEN4YX7K3JVvYY9Yw8egaOPtTpXmfEG/vT4KKRDyh8MgTirlCo3AKgwtC24pTbDPDG/zMQ2SlB k3OZIaGMzgxAJ+JCXZO4XmfTSdN2oSmbIXb17LFk= X-Received: by 2002:a05:6402:24d4:b0:6a7:ee54:f897 with SMTP id 4fb4d7f45d1cf-6aa2244349emr4232275a12.27.1789662334673; Thu, 17 Sep 2026 09:25:34 -0700 (PDT) Received: from c14-smtp-2023.dev.purestorage.com ([208.88.158.128]) by smtp-relay.gmail.com with ESMTPS id 4fb4d7f45d1cf-6aa1cf65559sm2670116a12.0.2026.09.17.09.25.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Sep 2026 09:25:34 -0700 (PDT) X-Relaying-Domain: everpuredata.com Received: from irdv-tmenninger.dev.purestorage.com (irdv-tmenninger.dev.purestorage.com [10.32.149.15]) by c14-smtp-2023.dev.purestorage.com (Postfix) with ESMTPS id 1A53034014B; Thu, 17 Sep 2026 09:25:33 -0700 (PDT) From: Tim Menninger To: Harry Yoo Cc: linux-mm@kvack.org, Chuck Lever , linux-nfs@vger.kernel.org, Jon Curley , Eric Badger , Vlastimil Babka , Andrew Morton , Hao Li , Christoph Lameter , David Rientjes , Roman Gushchin , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [SLUB] nfs_page cmpxchg_double_fail and perf lock perturbation on dual-socket NFS/RDMA Date: Thu, 17 Sep 2026 16:25:33 +0000 Message-Id: <20260917162533.600472-1-tmenninger@everpuredata.com> X-Mailer: git-send-email 2.34.1 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 It reproduces with slab_nomerge. I booted the same kernel with: $ cat /proc/cmdline ... slab_nomerge ... Uninstrumented throughput remains in the high-45 to low-46 GB/s range, as before. During perf lock it was around 30 GB/s in these runs, versus roughly 25 GB/s previously. The dominant lock measurements are essentially unchanged: default slab_nomerge unpinned/node0 contentions 4,782,839 4,858,759 total wait 14.39 min 14.26 min average wait 180.47 us 176.13 us node0/node0 contentions 4,582,012 4,686,729 total wait 14.13 min 14.34 min average wait 185.05 us 183.53 us unpinned/balanced contentions 4,572,196 4,544,677 total wait 12.81 min 12.56 min average wait 168.14 us 165.84 us The uninstrumented cmpxchg_double_fail deltas were: default slab_nomerge unpinned/node0 7,471 8,892 node0/node0 713 457 unpinned/balanced 1,503 1,504 The CPU-utilization change while perf lock is active also remains. System-wide %idle for uninstrumented/instrumented windows was: default slab_nomerge uninstr. instr. uninstr. instr. unpinned/node0 31.46% 3.60% 23.02% 2.15% node0/node0 84.26% 12.07% 84.62% 11.85% unpinned/balanced 66.86% 14.83% 66.58% 14.78% Thanks, Tim