/* * mm/percpu-km.c - kernel memory based chunk allocation * * Copyright (C) 2010 SUSE Linux Products GmbH * Copyright (C) 2010 Tejun Heo * * This file is released under the GPLv2. * * Chunks are allocated as a contiguous kernel memory using gfp * allocation. This is to be used on nommu architectures. * * To use percpu-km, * * - define CONFIG_NEED_PER_CPU_KM from the arch Kconfig. * * - CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK must not be defined. It's * not compatible with PER_CPU_KM. EMBED_FIRST_CHUNK should work * fine. * * - NUMA is not supported. When setting up the first chunk, * @cpu_distance_fn should be NULL or report all CPUs to be nearer * than or at LOCAL_DISTANCE. * * - It's best if the chunk size is power of two multiple of * PAGE_SIZE. Because each chunk is allocated as a contiguous * kernel memory block using alloc_pages(), memory will be wasted if * chunk size is not aligned. percpu-km code will whine about it. */ #if defined(CONFIG_SMP) && defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK) #error "contiguous percpu allocation is incompatible with paged first chunk" #endif #include static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int page_start, int page_end) { return 0; } static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int page_start, int page_end) { /* nada */ } static struct pcpu_chunk *pcpu_create_chunk(void) { const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT; struct pcpu_chunk *chunk; struct page *pages; int i; chunk = pcpu_alloc_chunk(); if (!chunk) return NULL; pages = alloc_pages(GFP_KERNEL, order_base_2(nr_pages)); if (!pages) { pcpu_free_chunk(chunk); return NULL; } for (i = 0; i < nr_pages; i++) pcpu_set_page_chunk(nth_page(pages, i), chunk); chunk->data = pages; chunk->base_addr = page_address(pages) - pcpu_group_offsets[0]; spin_lock_irq(&pcpu_lock); pcpu_chunk_populated(chunk, 0, nr_pages); spin_unlock_irq(&pcpu_lock); return chunk; } static void pcpu_destroy_chunk(struct pcpu_chunk *chunk) { const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT; if (chunk && chunk->data) __free_pages(chunk->data, order_base_2(nr_pages)); pcpu_free_chunk(chunk); } static struct page *pcpu_addr_to_page(void *addr) { return virt_to_page(addr); } static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai) { size_t nr_pages, alloc_pages; /* all units must be in a single group */ if (ai->nr_groups != 1) { pr_crit("can't handle more than one group\n"); return -EINVAL; } nr_pages = (ai->groups[0].nr_units * ai->unit_size) >> PAGE_SHIFT; alloc_pages = roundup_pow_of_two(nr_pages); if (alloc_pages > nr_pages) pr_warn("wasting %zu pages per chunk\n", alloc_pages - nr_pages); return 0; } /commit/net?id=79c6f448c8b79c321e4a1f31f98194e4f6b6cae7'>net/sched/act_meta_mark.c
diff options
context:
space:
mode:
authorSteven Rostedt (VMware) <rostedt@goodmis.org>2017-01-30 19:27:10 -0500
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2017-01-31 09:13:49 -0500
commit79c6f448c8b79c321e4a1f31f98194e4f6b6cae7 (patch)
tree370efda701f03cccf21e02bb1fdd3b852547d75c /net/sched/act_meta_mark.c
parent0c744ea4f77d72b3dcebb7a8f2684633ec79be88 (diff)
tracing: Fix hwlat kthread migration
The hwlat tracer creates a kernel thread at start of the tracer. It is pinned to a single CPU and will move to the next CPU after each period of running. If the user modifies the migration thread's affinity, it will not change after that happens. The original code created the thread at the first instance it was called, but later was changed to destroy the thread after the tracer was finished, and would not be created until the next instance of the tracer was established. The code that initialized the affinity was only called on the initial instantiation of the tracer. After that, it was not initialized, and the previous affinity did not match the current newly created one, making it appear that the user modified the thread's affinity when it did not, and the thread failed to migrate again. Cc: stable@vger.kernel.org Fixes: 0330f7aa8ee6 ("tracing: Have hwlat trace migrate across tracing_cpumask CPUs") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'net/sched/act_meta_mark.c')