From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E98075A109 for ; Tue, 20 Feb 2024 07:20:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.10 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708413616; cv=none; b=Roe846o+G9NOJyQGWodFXCdcXrahufL9XOrqwGn9dKf2oLa7pkhy3kg63gGtDAhk40C47OJFxQs++EZrb8rK6yY4ennp0JpijlQHuq3ngV7GifGBWlYZWZwUTjhvxLq93msWbORi0RWLpRWpXwYOiDKHGQ7hS2A1TP7fI6PAszw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708413616; c=relaxed/simple; bh=OHde8bTYZStDVq7VnJxwBpRl980/3rKekMTSgOwZ8Pw=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=H7bVx7T1mppsJor8hRZCG083Zn1xqRzsyg0m9Zz+Kgf6tlD6hdprQVzYk4tfJ3CeUrJ0wRwO7Qh7IYh74AfyFICPjk6QMBWmtRpmlSw21KLkxTXaI0cOVZQL7LMNN6VABunDvciz96wnBgHoUj7+COrsplDsEp/pJ7tejnSSwMI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=US5bUEHK; arc=none smtp.client-ip=198.175.65.10 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="US5bUEHK" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1708413615; x=1739949615; h=from:to:cc:subject:in-reply-to:references:date: message-id:mime-version; bh=OHde8bTYZStDVq7VnJxwBpRl980/3rKekMTSgOwZ8Pw=; b=US5bUEHK8TZwuGqzRhbntdG1nMZsbWjpSmkghueMVch8odXFw/GC0Y84 5AGrs6W5GzMiiKoRb2Qdil/CDxJaemF9YTfL/vhYkC+dCMOHFNpoJMG1b EJ/ZOpy2hWiQPvftclDm0HG1TOQ2HiQ2SveknHwUO2msdXYJXV0sLAHpW eaE+JDLXj5xGqricNSO8BuNK2EIQgxvGP1uSMRoTlWr+noQExUr4K5vzz vBFRQ134WCO5kAYCX72wwygsCj7B/MXGXrpNIsqEtL5dl/d3sh/M1h9fM KdMkf0HiCtRu9QLtoY2jX5r127zY/tr6fuPXrMhrGIfQDGy/i16LqSJYL w==; X-IronPort-AV: E=McAfee;i="6600,9927,10989"; a="19937358" X-IronPort-AV: E=Sophos;i="6.06,172,1705392000"; d="scan'208";a="19937358" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by orvoesa102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Feb 2024 23:20:14 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.06,172,1705392000"; d="scan'208";a="9308569" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by fmviesa004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Feb 2024 23:20:08 -0800 From: "Huang, Ying" To: Donet Tom Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Aneesh Kumar , Dave Hansen , Mel Gorman , Ben Widawsky , Feng Tang , Michal Hocko , Andrea Arcangeli , Peter Zijlstra , Ingo Molnar , Rik van Riel , Johannes Weiner , Matthew Wilcox , Mike Kravetz , Vlastimil Babka , Dan Williams , Hugh Dickins , Kefeng Wang , Suren Baghdasaryan Subject: Re: [PATCH 3/3] mm/numa_balancing:Allow migrate on protnone reference with MPOL_PREFERRED_MANY policy In-Reply-To: <8d7737208bd24e754dc7a538a3f7f02de84f1f72.1708097962.git.donettom@linux.ibm.com> (Donet Tom's message of "Sat, 17 Feb 2024 01:31:35 -0600") References: <9c3f7b743477560d1c5b12b8c111a584a2cc92ee.1708097962.git.donettom@linux.ibm.com> <8d7737208bd24e754dc7a538a3f7f02de84f1f72.1708097962.git.donettom@linux.ibm.com> Date: Tue, 20 Feb 2024 15:18:13 +0800 Message-ID: <877cizppsa.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ascii Donet Tom writes: > commit bda420b98505 ("numa balancing: migrate on fault among multiple bound > nodes") added support for migrate on protnone reference with MPOL_BIND > memory policy. This allowed numa fault migration when the executing node > is part of the policy mask for MPOL_BIND. This patch extends migration > support to MPOL_PREFERRED_MANY policy. > > Currently, we cannot specify MPOL_PREFERRED_MANY with the mempolicy flag > MPOL_F_NUMA_BALANCING. This causes issues when we want to use > NUMA_BALANCING_MEMORY_TIERING. To effectively use the slow memory tier, > the kernel should not allocate pages from the slower memory tier via > allocation control zonelist fallback. Instead, we should move cold pages > from the faster memory node via memory demotion. For a page allocation, > kswapd is only woken up after we try to allocate pages from all nodes in > the allocation zone list. This implies that, without using memory > policies, we will end up allocating hot pages in the slower memory tier. > > MPOL_PREFERRED_MANY was added by commit b27abaccf8e8 ("mm/mempolicy: add > MPOL_PREFERRED_MANY for multiple preferred nodes") to allow better > allocation control when we have memory tiers in the system. With > MPOL_PREFERRED_MANY, the user can use a policy node mask consisting only > of faster memory nodes. When we fail to allocate pages from the faster > memory node, kswapd would be woken up, allowing demotion of cold pages > to slower memory nodes. > > With the current kernel, such usage of memory policies implies we can't > do page promotion from a slower memory tier to a faster memory tier > using numa fault. This patch fixes this issue. > > For MPOL_PREFERRED_MANY, if the executing node is in the policy node > mask, we allow numa migration to the executing nodes. If the executing > node is not in the policy node mask but the folio is already allocated > based on policy preference (the folio node is in the policy node mask), > we don't allow numa migration. If both the executing node and folio node > are outside the policy node mask, we allow numa migration to the > executing nodes. > > Signed-off-by: Aneesh Kumar K.V (IBM) > Signed-off-by: Donet Tom > --- > mm/mempolicy.c | 28 ++++++++++++++++++++++++++-- > 1 file changed, 26 insertions(+), 2 deletions(-) > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index 73d698e21dae..8c4c92b10371 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -1458,9 +1458,10 @@ static inline int sanitize_mpol_flags(int *mode, unsigned short *flags) > if ((*flags & MPOL_F_STATIC_NODES) && (*flags & MPOL_F_RELATIVE_NODES)) > return -EINVAL; > if (*flags & MPOL_F_NUMA_BALANCING) { > - if (*mode != MPOL_BIND) > + if (*mode == MPOL_BIND || *mode == MPOL_PREFERRED_MANY) > + *flags |= (MPOL_F_MOF | MPOL_F_MORON); > + else > return -EINVAL; > - *flags |= (MPOL_F_MOF | MPOL_F_MORON); > } > return 0; > } > @@ -2463,6 +2464,23 @@ static void sp_free(struct sp_node *n) > kmem_cache_free(sn_cache, n); > } > > +static inline bool mpol_preferred_should_numa_migrate(int exec_node, int folio_node, > + struct mempolicy *pol) > +{ > + /* if the executing node is in the policy node mask, migrate */ > + if (node_isset(exec_node, pol->nodes)) > + return true; > + > + /* If the folio node is in policy node mask, don't migrate */ > + if (node_isset(folio_node, pol->nodes)) > + return false; > + /* > + * both the folio node and executing node are outside the policy nodemask, > + * migrate as normal numa fault migration. > + */ > + return true; Why? This may cause some unexpected result. For example, pages may be distributed among multiple sockets unexpectedly. So, I prefer the more conservative policy, that is, only migrate if this node is in pol->nodes. -- Best Regards, Huang, Ying > +} > + > /** > * mpol_misplaced - check whether current folio node is valid in policy > * > @@ -2526,6 +2544,12 @@ int mpol_misplaced(struct folio *folio, struct vm_area_struct *vma, > break; > > case MPOL_PREFERRED_MANY: > + if (pol->flags & MPOL_F_MORON) { > + if (!mpol_preferred_should_numa_migrate(thisnid, curnid, pol)) > + goto out; > + break; > + } > + > /* > * use current page if in policy nodemask, > * else select nearest allowed node, if any.