On 2021/10/15 5:48, Mike Kravetz wrote:
On 10/13/21 11:08 PM, Baolin Wang wrote:Now the size of CMA area for gigantic hugepages runtime allocation is balanced for all online nodes, but we also want to specify the size of CMA per-node, or only one node in some cases, which are similar with commit 86acc55c3d32 ("hugetlbfs: extend the definition of hugepages parameter to support node allocation")[1].I would not include the commit hash here. IIUC, this can change as it is moved to Linus' tree in the next merge window.
Sure.
For example, on some multi-nodes systems, each node's memory can be different, allocating the same size of CMA for each node is not suitable for the low-memory nodes. Meanwhile some workloads like DPDK mentioned by Zhenguo in patch [1] only need hugepages in one node. On the other hand, we have some machines with multiple types of memory, like DRAM and PMEM (persistent memory). On this system, we may want to specify all the hugepages only on DRAM node, or specify the proportion of DRAM node and PMEM node, to tuning the performance of the workloads. Thus this patch adds node format for 'hugetlb_cma' parameter to support specifying the size of CMA per-node. An example is as follows: hugetlb_cma=0:5G,2:5G which means allocating 5G size of CMA area on node 0 and node 2 respectively. And the users should use the node specific sysfs file to allocate the gigantic hugepages if specified the CMA size on that node. [1] https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@xxxxxxxxx Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx> --- Changes from v1: - Update the commit log. - Avoid changing the behavior for 'balanced' gigantic huge page pool allocations. - Catch the invalid node specified in hugetlb_cma_reserve(). - Validate the size of CMA for each node in hugetlb_cma_reserve(). --- Documentation/admin-guide/kernel-parameters.txt | 6 +- mm/hugetlb.c | 98 ++++++++++++++++++++++--- 2 files changed, 93 insertions(+), 11 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 3ad8e9d0..a147faa5 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1587,8 +1587,10 @@ registers. Default set by CONFIG_HPET_MMAP_DEFAULT.hugetlb_cma= [HW,CMA] The size of a CMA area used for allocation- of gigantic hugepages. - Format: nn[KMGTPE] + of gigantic hugepages. Or using node format, the size + of a CMA area per node can be specified. + Format: nn[KMGTPE] or (node format) + <node>:nn[KMGTPE][,<node>:nn[KMGTPE]]Reserve a CMA area of given size and allocate gigantichugepages using the CMA allocator. If enabled, the diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 6d2f4c2..ac9afc2 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -50,6 +50,7 @@#ifdef CONFIG_CMAstatic struct cma *hugetlb_cma[MAX_NUMNODES]; +static unsigned long hugetlb_cma_size_in_node[MAX_NUMNODES] __initdata; static bool hugetlb_cma_page(struct page *page, unsigned int order) { return cma_pages_valid(hugetlb_cma[page_to_nid(page)], page, @@ -62,6 +63,7 @@ static bool hugetlb_cma_page(struct page *page, unsigned int order) } #endif static unsigned long hugetlb_cma_size __initdata; +static nodemask_t hugetlb_cma_nodes_allowed = NODE_MASK_NONE;/** Minimum page order among possible hugepage sizes, set to a proper value @@ -3508,7 +3510,16 @@ static ssize_t __nr_hugepages_store_common(bool obey_mempolicy, /* * Node specific request. count adjustment happens in * set_max_huge_pages() after acquiring hugetlb_lock. + * + * If we've specified the size of CMA area per node for + * gigantic hugepages, should catch the warning if the + * nid is not in the 'hugetlb_cma_nodes_allowed' nodemask. */ + if (hstate_is_gigantic(h) && + !nodes_empty(hugetlb_cma_nodes_allowed) && + !node_isset(nid, hugetlb_cma_nodes_allowed)) + pr_warn("hugetlb_cma: no reservation on this node %d\n", nid); +I would prefer to drop this code and hugetlb_cma_nodes_allowed. Why? CMA is an alternative allocation mechanism for gigantic pages. The allocator will fall back to the normal allocator (alloc_contig_pages) if allocation from CMA fails.
Yes.
This warning implies that the user 'forgot' to reserve CMA on the specified node, or is perhaps allocating gigantic pages on the wrong node. We can not be sure this is the case. I agree that in most cases when a user requests node specific CMA reservations, they will likely want to perform gigantic page allocations on the same nodes. However, that may not always be the case and in such cases the warning could be confusing. We do not print warnings today when allocating huge pages via the proc/sysfs interfaces. We should not add one unless there is a very good reason.
OK. Will remove this in next version.
init_nodemask_of_node(&nodes_allowed, nid); n_mask = &nodes_allowed; } @@ -6745,7 +6756,38 @@ void hugetlb_unshare_all_pmds(struct vm_area_struct *vma)static int __init cmdline_parse_hugetlb_cma(char *p){ - hugetlb_cma_size = memparse(p, &p); + int nid, count = 0; + unsigned long tmp; + char *s = p; + + while (*s) { + if (sscanf(s, "%lu%n", &tmp, &count) != 1) + break; + + if (s[count] == ':') { + nid = tmp; + if (nid < 0 || nid >= MAX_NUMNODES) + break; + + s += count + 1; + tmp = memparse(s, &s); + hugetlb_cma_size_in_node[nid] = tmp; + hugetlb_cma_size += tmp; + + /* + * Skip the separator if have one, otherwise + * break the parsing. + */ + if (*s == ',') + s++; + else + break; + } else { + hugetlb_cma_size = memparse(p, &p); + break; + } + } + return 0; }@@ -6754,6 +6796,7 @@ static int __init cmdline_parse_hugetlb_cma(char *p)void __init hugetlb_cma_reserve(int order) { unsigned long size, reserved, per_node; + bool node_specific_cma_alloc = false; int nid;cma_reserve_called = true;@@ -6761,26 +6804,61 @@ void __init hugetlb_cma_reserve(int order) if (!hugetlb_cma_size) return;+ for (nid = 0; nid < MAX_NUMNODES; nid++) {+ if (hugetlb_cma_size_in_node[nid] == 0) + continue; + + if (!node_state(nid, N_ONLINE)) { + pr_warn("hugetlb_cma: invalid node %d specified\n", nid); + hugetlb_cma_size -= hugetlb_cma_size_in_node[nid]; + hugetlb_cma_size_in_node[nid] = 0; + continue; + } + + if (hugetlb_cma_size_in_node[nid] < (PAGE_SIZE << order)) { + pr_warn("hugetlb_cma: cma area of node %d should be at least %lu MiB\n", + nid, (PAGE_SIZE << order) / SZ_1M); + hugetlb_cma_size -= hugetlb_cma_size_in_node[nid]; + hugetlb_cma_size_in_node[nid] = 0; + } else { + node_specific_cma_alloc = true; + } + } + + /* Validate the CMA size again in case some invalid nodes specified. */ + if (!hugetlb_cma_size) + return; + if (hugetlb_cma_size < (PAGE_SIZE << order)) { pr_warn("hugetlb_cma: cma area should be at least %lu MiB\n", (PAGE_SIZE << order) / SZ_1M); return; }The series "hugetlb: add demote/split page functionality" https://lore.kernel.org/linux-mm/20211007181918.136982-1-mike.kravetz@xxxxxxxxxx/T/#mcb25f5edaa235b93dd0d0b8fb81ba15f0317feeb is in Andrew's tree and has modified the above to set hugetlb_cma_size to 0 before returning. Code in that series uses the varialbe hugetlb_cma_size to determine if CMA was reserved and can possibly be used for huge pages. If no CMA is reserved in this routine, it must be set to 0. The code below should be fine as it checks 'reserved' at the end of routine and sets hugetlb_cma_size to zero if !reserved before returning. Mostly wanted to point out the context conflict with Andrew's tree. He or you will need to fix this for the patch to apply.
Thanks, I will rebase the code in next version.
