diff options
Diffstat (limited to 'kernel/events/ring_buffer.c')
| -rw-r--r-- | kernel/events/ring_buffer.c | 29 |
1 files changed, 20 insertions, 9 deletions
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index 5130b119d0ae..d2aef87c7e9f 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -679,7 +679,15 @@ int rb_alloc_aux(struct perf_buffer *rb, struct perf_event *event, { bool overwrite = !(flags & RING_BUFFER_WRITABLE); int node = (event->cpu == -1) ? -1 : cpu_to_node(event->cpu); - int ret = -ENOMEM, max_order; + bool use_contiguous_pages = event->pmu->capabilities & ( + PERF_PMU_CAP_AUX_NO_SG | PERF_PMU_CAP_AUX_PREFER_LARGE); + /* + * Initialize max_order to 0 for page allocation. This allocates single + * pages to minimize memory fragmentation. This is overridden if the + * PMU needs or prefers contiguous pages (use_contiguous_pages = true). + */ + int max_order = 0; + int ret = -ENOMEM; if (!has_aux(event)) return -EOPNOTSUPP; @@ -689,8 +697,8 @@ int rb_alloc_aux(struct perf_buffer *rb, struct perf_event *event, if (!overwrite) { /* - * Watermark defaults to half the buffer, and so does the - * max_order, to aid PMU drivers in double buffering. + * Watermark defaults to half the buffer, to aid PMU drivers + * in double buffering. */ if (!watermark) watermark = min_t(unsigned long, @@ -698,16 +706,19 @@ int rb_alloc_aux(struct perf_buffer *rb, struct perf_event *event, (unsigned long)nr_pages << (PAGE_SHIFT - 1)); /* - * Use aux_watermark as the basis for chunking to - * help PMU drivers honor the watermark. + * If using contiguous pages, use aux_watermark as the basis + * for chunking to help PMU drivers honor the watermark. */ - max_order = get_order(watermark); + if (use_contiguous_pages) + max_order = get_order(watermark); } else { /* - * We need to start with the max_order that fits in nr_pages, - * not the other way around, hence ilog2() and not get_order. + * If using contiguous pages, we need to start with the + * max_order that fits in nr_pages, not the other way around, + * hence ilog2() and not get_order. */ - max_order = ilog2(nr_pages); + if (use_contiguous_pages) + max_order = ilog2(nr_pages); watermark = 0; } |