From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=95.215.58.132 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793234471; b=MiMY2bouUAxPyiYs76QBL2lCTGIg+rFHnVekofcsVFlPj0ZVLDeipT59BEsZyv9X1O6E a7M/bP53P9ZPO6xngCJpRf7Ij1v2bXCX2p1eFX6ywB1s4516RADv3klpCsGZYk5Ye7j8w f7i6Az4nDYdYeKvCyn1mX5HCjuTjR5jtywgWzvq27lXfpJ1CN0wfrI3a4pbx9npmgW5/2 R8Hsz4JGyPGCEsCgsq/yjz6rHBM94Bn+QkulfHq1cKsGmkILz33WGx7wzxeuMyU2kcyvG rAPpI0L2yRyvb0nf76lPXpuQ5+guP2XqQX5w6j9JweBP2SJ9wfRwqJuXOFEyMg2YcBg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793234471; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:Date:From:To:Cc:Subject:Message-ID: References:MIME-Version:Content-Type:Content-Disposition:In-Reply-To; bh=zgify3Ps3ysA38ANbUdTtbw6FPLHnNTTLVy0kFUYagE=; b=zGr+hDs5k+7Emv8TfKIuR2ON79BSL+kPwRR+X9oEcFIeZEKTIPvWbynPDAf1tPzc11wp Uyp5rbeHztd4xoK5Waa+1u/lsc+6k7TzBaZMvVmaFsgvwuEM6AfTIjZETHfyLjq0W7NQT 5h6pOjHRD/MYQSkTGGWc2uyGh3uPQr9FQl6OBGeqFJ0Ax0iJ2soCc5P2rUgbCf20y46Q/ 8+R/IwMwpf4VNNDfA/NCQkW4QSVF2fDoMAth89aw6NPKrp7axtIWB13b8YBhRar3r0lq7 qfOOSFtgt1dxzFLZ3zhI5oz7ixRb4oZeu5qxk+w6iu4Vz+niw6hjvJPZwm8YQUGu4ng== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=d5frwqjH; arc=none smtp.remote-ip=95.215.58.132 Received: from mta1.migadu.com (out-132.mta1.migadu.com [95.215.58.132]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2D67A606A31C for ; Thu, 29 Oct 2026 00:41:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 2D67A606A31C Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=d5frwqjH X-Envelope-To: cgroups@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=nrCLj71iMMOCDy6LERksd1mB3zJ6XRfaBd4m3WwX4io=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1793234467; v=1; x=1793839267; b=d5frwqjHyL97fFmnsdltsvEUxy5DHaklkneaNh7rhm9TdwopHUxRM+Xnk8+OJW90ia7utOWa ae/kZICg72dTjmTBViPRsbrZkPxnhOgUaEv3AinPq2MpfX3xSkhjf7bH2niVuegg3lVE3KY7MfE vkeuT0vloYJEbHb22g4UnSS0= X-Envelope-To: cgroups@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 07904de55bd63c7d; Thu, 29 Oct 2026 00:41:06 +0000 X-Mizu-Trace-ID: 07904de55bd63c7d X-Migadu-Flow: FLOW_OUT Date: Wed, 28 Oct 2026 17:41:04 -0700 From: Shakeel Butt To: Kuniyuki Iwashima Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Kuniyuki Iwashima , linux-mm@kvack.org, cgroups@vger.kernel.org, yosry@kernel.org, joannelkoong@gmail.com Subject: Re: [PATCH v2 0/6] memcg: Batch mod_memcg_state() for MEMCG_SOCK. Message-ID: References: <20261028185034.3607746-1-kuniyu@google.com> X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261028185034.3607746-1-kuniyu@google.com> On Wed, Oct 28, 2026 at 06:50:12PM +0000, Kuniyuki Iwashima wrote: > On our production fleet, we saw mem_cgroup_sk_charge() spent over > 3x the cycles of try_charge_memcg() although the former should be > a thin wrapper of the latter. > > Looking at perf during tcp_rr, most of the cycles were spent in > mod_memcg_state(MEMCG_SOCK), which incurred two heavy memory stalls > due to cache line misses. (see patch 4) > > Also, tcp_rr w/ 20000 flows throughput often degrades by ~50% on > many core machine. (see patch 5) > > This series adds nr_sock[] to struct memcg_stock_pcp to batch > mod_memcg_state() for MEMCG_SOCK and move heavy operations to > out of local_lock(&memcg_stock.lock). > > With this series, tcp_rr w/ 10000 flows achieves 31% more > throughput with lower latency on machine w/ AMD EPYC 7B12 64-Core > Processor (Zen 2 Rome, 2 sockets, 256 vCPU) > > tcp_rr (10000 flows, 128 threads, 60s, average of 3 runs): > > Metric | Baseline | Patched | Diff > ---------------------------+----------------+----------------+-------- > Throughput (RPS) | 20,884,499 | 27,466,490 | +31.52% > Latency Mean (us) | 478.46 | 363.71 | -23.98% > Latency p50 (us) | 453.96 | 356.68 | -21.43% > Latency p90 (us) | 669.00 | 479.56 | -28.32% > Latency p99 (us) | 969.38 | 617.80 | -36.27% > > > Changes: > v2: > * Rebased on mm.git/mm-new > * Add patch 5 for flaky throughput issue > * Patch 4: > * Benchmark again after rebase and update numbers > * Check in_nmi() in __refill_stock() > > v1: https://lore.kernel.org/linux-mm/20261016052811.3085635-1-kuniyu@google.com/ > > > Kuniyuki Iwashima (6): > memcg: Remove unnecessary READ_ONCE() under memcg_stock.lock. > memcg: Reduce nesting in consume_stock() and refill_stock(). > memcg: Annotate slow paths in consume_stock() and refill_stock(). > memcg: Batch mod_memcg_state() for MEMCG_SOCK. > memcg: Uncharge pages outside memcg_stock.lock in __refill_stock(). > selftests: cgroup: Deflake test_memcg_sock() in test_memcontrol.c. Decouple the 4th patch (batch MEMCG_STOCK) from the remaining and send the remaining patches separately and upfront. For the 4th patch, I would prefer we first try to move the network sockets from memcg to objcg path. Then I would prefer we optimize the stats update for all stats instead of special casing for MEMCG_STOCK.