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X-IronPort-AV: E=McAfee;i="6500,9779,10548"; a="402141887" X-IronPort-AV: E=Sophos;i="5.96,210,1665471600"; d="scan'208";a="402141887" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Dec 2022 19:26:37 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10548"; a="733661676" X-IronPort-AV: E=Sophos;i="5.96,210,1665471600"; d="scan'208";a="733661676" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Dec 2022 19:26:33 -0800 From: "Huang, Ying" To: Mina Almasry Cc: Yang Shi , Yosry Ahmed , Tim Chen , weixugc@google.com, shakeelb@google.com, gthelen@google.com, fvdl@google.com, Tejun Heo , Zefan Li , Johannes Weiner , Jonathan Corbet , Michal Hocko , Roman Gushchin , Muchun Song , Andrew Morton , cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC PATCH v2] mm: Add nodes= arg to memory.reclaim References: <20221130020328.1009347-1-almasrymina@google.com> Date: Fri, 02 Dec 2022 11:25:44 +0800 In-Reply-To: <20221130020328.1009347-1-almasrymina@google.com> (Mina Almasry's message of "Tue, 29 Nov 2022 18:03:27 -0800") Message-ID: <878rjq32rr.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: B6F60140005 X-Stat-Signature: ptex4yhpdit4su4481gf9pxcpz7beuxq X-Spamd-Result: default: False [-3.90 / 9.00]; BAYES_HAM(-3.00)[100.00%]; DMARC_POLICY_ALLOW(-0.50)[intel.com,none]; R_SPF_ALLOW(-0.20)[+ip4:192.55.52.43/32]; R_DKIM_ALLOW(-0.20)[intel.com:s=Intel]; MIME_GOOD(-0.10)[text/plain]; RCVD_NO_TLS_LAST(0.10)[]; FROM_EQ_ENVFROM(0.00)[]; RCPT_COUNT_TWELVE(0.00)[20]; DKIM_TRACE(0.00)[intel.com:+]; MID_RHS_MATCH_FROMTLD(0.00)[]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCVD_COUNT_THREE(0.00)[3]; FROM_HAS_DN(0.00)[]; MIME_TRACE(0.00)[0:+]; TO_DN_SOME(0.00)[]; ARC_SIGNED(0.00)[hostedemail.com:s=arc-20220608:i=1]; ARC_NA(0.00)[] X-Rspam-User: X-HE-Tag: 1669951599-211451 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Mina Almasry writes: > The nodes= arg instructs the kernel to only scan the given nodes for > proactive reclaim. For example use cases, consider a 2 tier memory system: > > nodes 0,1 -> top tier > nodes 2,3 -> second tier > > $ echo "1m nodes=0" > memory.reclaim > > This instructs the kernel to attempt to reclaim 1m memory from node 0. > Since node 0 is a top tier node, demotion will be attempted first. This > is useful to direct proactive reclaim to specific nodes that are under > pressure. > > $ echo "1m nodes=2,3" > memory.reclaim > > This instructs the kernel to attempt to reclaim 1m memory in the second tier, > since this tier of memory has no demotion targets the memory will be > reclaimed. > > $ echo "1m nodes=0,1" > memory.reclaim > > Instructs the kernel to reclaim memory from the top tier nodes, which can > be desirable according to the userspace policy if there is pressure on > the top tiers. Since these nodes have demotion targets, the kernel will > attempt demotion first. > > Since commit 3f1509c57b1b ("Revert "mm/vmscan: never demote for memcg > reclaim""), the proactive reclaim interface memory.reclaim does both > reclaim and demotion. Reclaim and demotion incur different latency costs > to the jobs in the cgroup. Demoted memory would still be addressable > by the userspace at a higher latency, but reclaimed memory would need to > incur a pagefault. > > The 'nodes' arg is useful to allow the userspace to control demotion > and reclaim independently according to its policy: if the memory.reclaim > is called on a node with demotion targets, it will attempt demotion first; > if it is called on a node without demotion targets, it will only attempt > reclaim. > > Signed-off-by: Mina Almasry > --- > Documentation/admin-guide/cgroup-v2.rst | 15 +++--- > include/linux/swap.h | 3 +- > mm/memcontrol.c | 67 ++++++++++++++++++++----- > mm/vmscan.c | 4 +- > 4 files changed, 68 insertions(+), 21 deletions(-) > > diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst > index 74cec76be9f2..ac5fcbcd5ae6 100644 > --- a/Documentation/admin-guide/cgroup-v2.rst > +++ b/Documentation/admin-guide/cgroup-v2.rst > @@ -1245,17 +1245,13 @@ PAGE_SIZE multiple when read back. > This is a simple interface to trigger memory reclaim in the > target cgroup. > > - This file accepts a single key, the number of bytes to reclaim. > - No nested keys are currently supported. > + This file accepts a string which contains the number of bytes to > + reclaim. > > Example:: > > echo "1G" > memory.reclaim > > - The interface can be later extended with nested keys to > - configure the reclaim behavior. For example, specify the > - type of memory to reclaim from (anon, file, ..). > - > Please note that the kernel can over or under reclaim from > the target cgroup. If less bytes are reclaimed than the > specified amount, -EAGAIN is returned. > @@ -1267,6 +1263,13 @@ PAGE_SIZE multiple when read back. > This means that the networking layer will not adapt based on > reclaim induced by memory.reclaim. > > + This file also allows the user to specify the nodes to reclaim from, > + via the 'nodes=' key, example:: > + > + echo "1G nodes=0,1" > memory.reclaim > + > + The above instructs the kernel to reclaim memory from nodes 0,1. > + > memory.peak > A read-only single value file which exists on non-root > cgroups. > diff --git a/include/linux/swap.h b/include/linux/swap.h > index b61e2007d156..f542c114dffd 100644 > --- a/include/linux/swap.h > +++ b/include/linux/swap.h > @@ -419,7 +419,8 @@ extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order, > extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg, > unsigned long nr_pages, > gfp_t gfp_mask, > - unsigned int reclaim_options); > + unsigned int reclaim_options, > + nodemask_t nodemask); > extern unsigned long mem_cgroup_shrink_node(struct mem_cgroup *mem, > gfp_t gfp_mask, bool noswap, > pg_data_t *pgdat, > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 23750cec0036..a0d7850173a9 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -63,6 +63,7 @@ > #include > #include > #include > +#include > #include "internal.h" > #include > #include > @@ -2392,7 +2393,8 @@ static unsigned long reclaim_high(struct mem_cgroup *memcg, > psi_memstall_enter(&pflags); > nr_reclaimed += try_to_free_mem_cgroup_pages(memcg, nr_pages, > gfp_mask, > - MEMCG_RECLAIM_MAY_SWAP); > + MEMCG_RECLAIM_MAY_SWAP, > + NODE_MASK_ALL); > psi_memstall_leave(&pflags); > } while ((memcg = parent_mem_cgroup(memcg)) && > !mem_cgroup_is_root(memcg)); > @@ -2683,7 +2685,8 @@ static int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask, > > psi_memstall_enter(&pflags); > nr_reclaimed = try_to_free_mem_cgroup_pages(mem_over_limit, nr_pages, > - gfp_mask, reclaim_options); > + gfp_mask, reclaim_options, > + NODE_MASK_ALL); > psi_memstall_leave(&pflags); > > if (mem_cgroup_margin(mem_over_limit) >= nr_pages) > @@ -3503,7 +3506,8 @@ static int mem_cgroup_resize_max(struct mem_cgroup *memcg, > } > > if (!try_to_free_mem_cgroup_pages(memcg, 1, GFP_KERNEL, > - memsw ? 0 : MEMCG_RECLAIM_MAY_SWAP)) { > + memsw ? 0 : MEMCG_RECLAIM_MAY_SWAP, > + NODE_MASK_ALL)) { > ret = -EBUSY; > break; > } > @@ -3614,7 +3618,8 @@ static int mem_cgroup_force_empty(struct mem_cgroup *memcg) > return -EINTR; > > if (!try_to_free_mem_cgroup_pages(memcg, 1, GFP_KERNEL, > - MEMCG_RECLAIM_MAY_SWAP)) > + MEMCG_RECLAIM_MAY_SWAP, > + NODE_MASK_ALL)) > nr_retries--; > } > > @@ -6407,7 +6412,8 @@ static ssize_t memory_high_write(struct kernfs_open_file *of, > } > > reclaimed = try_to_free_mem_cgroup_pages(memcg, nr_pages - high, > - GFP_KERNEL, MEMCG_RECLAIM_MAY_SWAP); > + GFP_KERNEL, MEMCG_RECLAIM_MAY_SWAP, > + NODE_MASK_ALL); > > if (!reclaimed && !nr_retries--) > break; > @@ -6456,7 +6462,8 @@ static ssize_t memory_max_write(struct kernfs_open_file *of, > > if (nr_reclaims) { > if (!try_to_free_mem_cgroup_pages(memcg, nr_pages - max, > - GFP_KERNEL, MEMCG_RECLAIM_MAY_SWAP)) > + GFP_KERNEL, MEMCG_RECLAIM_MAY_SWAP, > + NODE_MASK_ALL)) > nr_reclaims--; > continue; > } > @@ -6579,21 +6586,54 @@ static ssize_t memory_oom_group_write(struct kernfs_open_file *of, > return nbytes; > } > > +enum { > + MEMORY_RECLAIM_NODES = 0, > + MEMORY_RECLAIM_NULL, > +}; > + > +static const match_table_t if_tokens = { > + { MEMORY_RECLAIM_NODES, "nodes=%s" }, > + { MEMORY_RECLAIM_NULL, NULL }, > +}; > + > static ssize_t memory_reclaim(struct kernfs_open_file *of, char *buf, > size_t nbytes, loff_t off) > { > struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); > unsigned int nr_retries = MAX_RECLAIM_RETRIES; > unsigned long nr_to_reclaim, nr_reclaimed = 0; > - unsigned int reclaim_options; > - int err; > + unsigned int reclaim_options = MEMCG_RECLAIM_MAY_SWAP | > + MEMCG_RECLAIM_PROACTIVE; > + char *old_buf, *start; > + substring_t args[MAX_OPT_ARGS]; > + int token; > + char value[256]; > + nodemask_t nodemask = NODE_MASK_ALL; > > buf = strstrip(buf); > - err = page_counter_memparse(buf, "", &nr_to_reclaim); > - if (err) > - return err; > > - reclaim_options = MEMCG_RECLAIM_MAY_SWAP | MEMCG_RECLAIM_PROACTIVE; > + old_buf = buf; > + nr_to_reclaim = memparse(buf, &buf) / PAGE_SIZE; > + if (buf == old_buf) > + return -EINVAL; > + > + buf = strstrip(buf); > + > + while ((start = strsep(&buf, " ")) != NULL) { > + if (!strlen(start)) > + continue; > + token = match_token(start, if_tokens, args); > + match_strlcpy(value, args, sizeof(value)); Per my understanding, we don't need to copy the string, because strsep() has replaced " " with "\0". Right? Best Regards, Huang, Ying > + switch (token) { > + case MEMORY_RECLAIM_NODES: > + if (nodelist_parse(value, nodemask) < 0) > + return -EINVAL; > + break; > + default: > + return -EINVAL; > + } > + } > + > while (nr_reclaimed < nr_to_reclaim) { > unsigned long reclaimed; > > @@ -6610,7 +6650,8 @@ static ssize_t memory_reclaim(struct kernfs_open_file *of, char *buf, > > reclaimed = try_to_free_mem_cgroup_pages(memcg, > nr_to_reclaim - nr_reclaimed, > - GFP_KERNEL, reclaim_options); > + GFP_KERNEL, reclaim_options, > + nodemask); > > if (!reclaimed && !nr_retries--) > return -EAGAIN; > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 7b8e8e43806b..23fc5b523764 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -6735,7 +6735,8 @@ unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg, > unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg, > unsigned long nr_pages, > gfp_t gfp_mask, > - unsigned int reclaim_options) > + unsigned int reclaim_options, > + nodemask_t nodemask) > { > unsigned long nr_reclaimed; > unsigned int noreclaim_flag; > @@ -6750,6 +6751,7 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg, > .may_unmap = 1, > .may_swap = !!(reclaim_options & MEMCG_RECLAIM_MAY_SWAP), > .proactive = !!(reclaim_options & MEMCG_RECLAIM_PROACTIVE), > + .nodemask = &nodemask, > }; > /* > * Traverse the ZONELIST_FALLBACK zonelist of the current node to put > -- > 2.38.1.584.g0f3c55d4c2-goog