From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yw1-f195.google.com (mail-yw1-f195.google.com [209.85.128.195]) (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 F2DE33859D5 for ; Fri, 23 Jan 2026 04:57:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.195 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769144275; cv=none; b=FP5dAu5vXh1NV49BPRY5O0NoCHh8tGmaNRxiTs3+pUHUgGQx2IfQIA0BsEl7T5EMbcGjLWC4EJOtIWTwbVTEfPOiGJ50Vi2W3FZ/MKXpWOVeg/wvswby4RRW2DEruh/NN2f8cLElh0lI4NS74j2fkS6jA5JzRMozNh0FyFAoOfo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769144275; c=relaxed/simple; bh=REwnbFI5Ih419YIeGbeMhAV79Y8hP0BScdx6C3Cv9Aw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ICiF2t58CajXAlTH7225Nm8UTILapCiWuWniEAoOn9DDyjXYKTDfJSRo0wXx7+Sn2D4/CDg5AZYdYBjohIDeN+bkjmID/jS4PvTwN7+GN54qxeaziDDc1gqDIhr3zHuL4Tuv+S9TCCXwjcGt+9mPExduva8WBAufElRRnLdb3lE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=ncaAgYsa; arc=none smtp.client-ip=209.85.128.195 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ncaAgYsa" Received: by mail-yw1-f195.google.com with SMTP id 00721157ae682-7927b1620ddso26722257b3.0 for ; Thu, 22 Jan 2026 20:57:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1769144267; x=1769749067; darn=lists.linux.dev; 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; bh=W2Hj3YMXyp6jb16WaA5iRCtpYS8eji7c2VCvrHXWtMA=; b=ncaAgYsauOnj6N+waJP7eFg66fssha7GX+3lN2MPI7w8gbXdH4Wjq0QyNoe6MAT5i5 mV7eRlJXDsi/lOnqs3GknvCiVtInAu4V5qcFFkIJ78xTWHR+6pHC2QZWOuFVjN9sTCp3 K3T6uHVSNowsxBxp7RKh3uUZ7ub+EHxtL0gUs0CUGLTT7OaNj6rt1g4H5959htTmwW97 ox/4N+OYzuDfz7pZuEInonYrVsuMV5c8KG4ROs6CAEFDBFR5yduOc+q8aijaq69TSw2h 852fYYDKD9g22hyCLXzR3UNgynoAGIu5Sqp5VEmBC5m3E9lU3MoAP3QJNaEp1Mn2HN28 zg3g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1769144267; x=1769749067; 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; bh=W2Hj3YMXyp6jb16WaA5iRCtpYS8eji7c2VCvrHXWtMA=; b=YKEWpM69MYNZg/tQsjhInMxt2Ki0edYXMR5brQovsLoB80N6+kzLnqCqZdMi5MtFSf GwDVs6q/WlivvvJvQxlaF+Bx+C5uRB96bscmkcxwbQLr3CeXpYnWfAtfsDF0WeGMskEV OW2CIvK0d6cCqnP6mGi9URTKgBSs4g7uf1JtLuJxvKxSPFUy8wPIwCO3ImXeju8W5XyQ 5KVbYVwiKEUr3ZFIC3PqPZzWGkrL0rY/ErHNle3z+NRErRNIrZ2zl+v1K20/PPFrlOXv gVAKuZbK/gMQV+txKnjzpOAkfk9sBkoOFHO1Y/XFcDrmOtrdSTkMV2Z06DKS5PFpPqyg eMvA== X-Gm-Message-State: AOJu0Yyj3+nrPmnS8kAXiNfYdUw71g1Qn2brzBxa0FCUgspkh0ukPGEG fpZdZGYTIiiMpW+D6bQKYgIdPlRpB0JInAZHcoq3SkBl3N/6Ui1Y1hcN417ruk0= X-Gm-Gg: AZuq6aJUn6Ao0OpkZ8EU2AgEOQUAZgY6xRPjulLMvrRhM/5P2SVeyFxc2emuurey/69 yH5SsDLY8ML0nL4NV28y31n752NVMVnWmZgK6u4H7C+D4TYaRru6ulQYXMV/nMCcsegzvIr2N0/ utFFveWYHffNw1mJJeSj/gWL5kEtECRsdWbYj25+w2uAoJMQtpAkwwC0RIRNOUdGEjh82NoyArl XuxGyNeOwkjj+t9Gb+4gTnFOvGVx92CaRHX0KzdWq59GXloEM+F5eSOY+imoAhC7DKD8jDvW1jo OfAsRlqOHWJ3ZWbH+HkXDxtd51JHZEP5tDffrq8roAiQY5eLjev43ryZLasT1ihI1XpqQj4wLnH PCVwnA9wUBi55rC9EgCLLxBkrUUiRsGIVCjbESxHmMqARybyv/qpyiZmzl8Xlwavb1jbIGohn2m yJyOzFkMZ0WtIwVsm9c9Fyhd36VEvPC+dmbdwZe0FsMcdnB8i80eyyaT0j38k/oA== X-Received: by 2002:a05:690c:688f:b0:794:1f46:79eb with SMTP id 00721157ae682-7942a70b7dcmr45404977b3.5.1769144267450; Thu, 22 Jan 2026 20:57:47 -0800 (PST) Received: from localhost (23-116-43-216.lightspeed.sntcca.sbcglobal.net. [23.116.43.216]) by smtp.gmail.com with ESMTPSA id 00721157ae682-7943af14432sm6354717b3.8.2026.01.22.20.57.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Jan 2026 20:57:47 -0800 (PST) From: Ravi Jonnalagadda To: damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org Cc: sj@kernel.org, akpm@linux-foundation.org, corbet@lwn.net, bijan311@gmail.com, ajayjoshi@micron.com, Ravi Jonnalagadda Subject: [RFC PATCH 4/5] mm/damon/paddr: capacity clamp and directional early-exit for node_sys_bp Date: Thu, 22 Jan 2026 20:57:27 -0800 Message-ID: <20260123045733.6954-5-ravis.opensrc@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260123045733.6954-1-ravis.opensrc@gmail.com> References: <20260123045733.6954-1-ravis.opensrc@gmail.com> Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Clamp effective target to node capacity (bp) and skip in-migration if the node already meets/exceeds it. This avoids oscillation and unnecessary work in two-context DRAM/CXL setups when quota goals (e.g., node_sys_bp) are met. Signed-off-by: Ravi Jonnalagadda --- mm/damon/paddr.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c index 30e4e5663dcb..64dbdd2196a5 100644 --- a/mm/damon/paddr.c +++ b/mm/damon/paddr.c @@ -300,10 +300,54 @@ static unsigned long damon_pa_deactivate_pages(struct damon_region *r, sz_filter_passed); } +static unsigned long damon_pa_node_capacity_bp(int nid) +{ + struct pglist_data *pgdat; + unsigned long sys_total = damon_pa_totalram_bytes(); + unsigned long node_pages, node_total; + + if (nid < 0 || !sys_total) + return 0; + pgdat = NODE_DATA(nid); + if (!pgdat) + return 0; + node_pages = pgdat->node_spanned_pages; + node_total = node_pages << PAGE_SHIFT; + return div64_u64((u64)node_total * 10000ULL, sys_total); +} + static unsigned long damon_pa_migrate(struct damon_region *r, unsigned long addr_unit, struct damos *s, unsigned long *sz_filter_passed) { + /* + * Capacity clamp + directional early-exit for node_sys_bp goals: + * If we are migrating INTO g->nid and the current bp for that node is + * already >= min(target_bp, capacity_bp), skip work this interval. + */ + { + struct damos_quota_goal *g; + + list_for_each_entry(g, &s->quota.goals, list) { + unsigned long cap_bp, effective_target_bp; + + if (g->metric != DAMOS_QUOTA_NODE_SYS_BP) + continue; + if (g->nid < 0) + continue; + + cap_bp = damon_pa_node_capacity_bp(g->nid); + if (!cap_bp) + break; + + effective_target_bp = min(g->target_value, cap_bp); + if (s->target_nid == g->nid && + g->current_value >= effective_target_bp) + return 0; + break; + } + } + phys_addr_t addr, applied; LIST_HEAD(folio_list); struct folio *folio; -- 2.43.0