Messages in this thread | | | Subject | Re: [PATCH] hugetlb: Support node specified when using cma for gigantic hugepages | From | Baolin Wang <> | Date | Thu, 14 Oct 2021 10:39:25 +0800 |
| |
在 2021/10/14 10:30, Mike Kravetz 写道: > On 10/13/21 7:23 PM, Baolin Wang wrote: >> >> >> On 2021/10/14 6:06, Mike Kravetz wrote: >>> On 10/9/21 10:24 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]. >>>> >>>> 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. >>>> >>>> [1] >>>> https://lkml.kernel.org/r/20211005054729.86457-1-yaozhenguo1@gmail.com >>>> >>>> Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> >>>> --- >>>> Documentation/admin-guide/kernel-parameters.txt | 6 +- >>>> mm/hugetlb.c | 79 +++++++++++++++++++++---- >>>> 2 files changed, 73 insertions(+), 12 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 gigantic >>>> hugepages using the CMA allocator. If enabled, the >>>> diff --git a/mm/hugetlb.c b/mm/hugetlb.c >>>> index 6d2f4c2..8b4e409 100644 >>>> --- a/mm/hugetlb.c >>>> +++ b/mm/hugetlb.c >>>> @@ -50,6 +50,7 @@ >>>> #ifdef CONFIG_CMA >>>> static 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 >>>> @@ -3497,9 +3499,15 @@ static ssize_t __nr_hugepages_store_common(bool obey_mempolicy, >>>> if (nid == NUMA_NO_NODE) { >>>> /* >>>> + * If we've specified the size of CMA area per node, >>>> + * should use it firstly. >>>> + */ >>>> + if (hstate_is_gigantic(h) && !nodes_empty(hugetlb_cma_nodes_allowed)) >>>> + n_mask = &hugetlb_cma_nodes_allowed; >>>> + /* >>> >>> IIUC, this changes the behavior for 'balanced' gigantic huge page pool >>> allocations if per-node hugetlb_cma is specified. It will now only >>> attempt to allocate gigantic pages on nodes where CMA was reserved. >>> Even if we run out of space on the node, it will not go to other nodes >>> as before. Is that correct? >> >> Right. >> >>> >>> I do not believe we want this change in behavior. IMO, if the user is >>> doing node specific CMA reservations, then the user should use the node >>> specific sysfs file for pool allocations on that node. >> >> Sounds more reasonable, will move 'hugetlb_cma_nodes_allowed' to the node specific allocation. >> >>>> * global hstate attribute >>>> */ >>>> - if (!(obey_mempolicy && >>>> + else if (!(obey_mempolicy && >>>> init_nodemask_of_mempolicy(&nodes_allowed))) >>>> n_mask = &node_states[N_MEMORY]; >>>> else >>>> @@ -6745,7 +6753,38 @@ 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; >>> >>> nid can only be compared to MAX_NUMNODES because this an early param >>> before numa is setup and we do not know exactly how many nodes there >>> are. Is this correct? >> >> Yes. >> >>> >>> Suppose one specifies an invaid node. For example, on my 2 node system >>> I use the option 'hugetlb_cma=2:2G'. This is not flagged as an error >>> during processing and 1G CMA is reserved on node 0 and 1G is reserved >>> on node 1. Is that by design, or just chance? >> >> Actually we won't allocate any CMA area in this case, since in hugetlb_cma_reserve(), we will only iterate the online nodes to try to allocate CMA area, and node 2 is not in the range of online nodes in this case. >> > > But, since it can not do node specifric allocations it falls through to > the all nodes case? Here is what I see: > > # numactl -H > available: 2 nodes (0-1) > node 0 cpus: 0 1 > node 0 size: 8053 MB > node 0 free: 6543 MB > node 1 cpus: 2 3 > node 1 size: 8150 MB > node 1 free: 4851 MB > node distances: > node 0 1 > 0: 10 20 > 1: 20 10 > > # reboot > > # dmesg | grep -i huge > [ 0.000000] Command line: BOOT_IMAGE=/vmlinuz-5.15.0-rc4-mm1+ root=/dev/mapper/fedora_new--host-root ro rd.lvm.lv=fedora_new-host/root rd.lvm.lv=fedora_new-host/swap console=tty0 console=ttyS0,115200 audit=0 transparent_hugepage=always hugetlb_free_vmemmap=on hugetlb_cma=2:2G > [ 0.008345] hugetlb_cma: reserve 2048 MiB, up to 1024 MiB per node > [ 0.008349] hugetlb_cma: reserved 1024 MiB on node 0 > [ 0.008352] hugetlb_cma: reserved 1024 MiB on node 1 > [ 0.053682] Kernel command line: BOOT_IMAGE=/vmlinuz-5.15.0-rc4-mm1+ root=/dev/mapper/fedora_new--host-root ro rd.lvm.lv=fedora_new-host/root rd.lvm.lv=fedora_new-host/swap console=tty0 console=ttyS0,115200 audit=0 transparent_hugepage=always hugetlb_free_vmemmap=on hugetlb_cma=2:2G > [ 0.401648] HugeTLB: can free 4094 vmemmap pages for hugepages-1048576kB > [ 0.413681] HugeTLB: can free 6 vmemmap pages for hugepages-2048kB > [ 0.414590] HugeTLB registered 1.00 GiB page size, pre-allocated 0 pages > [ 0.415653] HugeTLB registered 2.00 MiB page size, pre-allocated 0 pages
Oh, I see. I only validate the online nodes to check if we've specified the size of CMA, so in this case, it will fall back to the original balanced policy. As you said, I should catch the invalid nodes in hugetlb_cma_reserve() to avoid this isse. Thanks for pointing out the issue.
+ for_each_node_state(nid, N_ONLINE) { + if (hugetlb_cma_size_in_node[nid] > 0) { + node_specific_cma_alloc = true; + break; + } + }
| |