On 30/06/2021 04:51, Ming Lei wrote:
The default queue mapping builder of blk_mq_map_queues doesn't take NUMA topo into account, so the built mapping is pretty bad, since CPUs belonging to different NUMA node are assigned to same queue. It is observed that IOPS drops by ~30% when running two jobs on same hctx of null_blk from two CPUs belonging to two NUMA nodes compared with from same NUMA node. Address the issue by reusing irq_create_affinity_masks() for building the default queue mapping, so that we can re-use the mapping created for managed irq. Lots of drivers may benefit from the change, such as nvme pci poll, nvme tcp, ... Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> --- block/blk-mq-cpumap.c | 60 +++++++++---------------------------------- 1 file changed, 12 insertions(+), 48 deletions(-) diff --git a/block/blk-mq-cpumap.c b/block/blk-mq-cpumap.c index 3db84d3197f1..946e373296a3 100644 --- a/block/blk-mq-cpumap.c +++ b/block/blk-mq-cpumap.c @@ -10,67 +10,31 @@ #include <linux/mm.h> #include <linux/smp.h> #include <linux/cpu.h> +#include <linux/interrupt.h>
Similar to what Christoph mentioned, seems strange to be including interrupt.h
#include <linux/blk-mq.h>#include "blk.h" #include "blk-mq.h"-static int queue_index(struct blk_mq_queue_map *qmap,- unsigned int nr_queues, const int q) -{ - return qmap->queue_offset + (q % nr_queues); -} - -static int get_first_sibling(unsigned int cpu) -{ - unsigned int ret; - - ret = cpumask_first(topology_sibling_cpumask(cpu)); - if (ret < nr_cpu_ids) - return ret; - - return cpu; -} - int blk_mq_map_queues(struct blk_mq_queue_map *qmap) { + struct irq_affinity_desc *masks = NULL; + struct irq_affinity affd = {0};
should this be simply {}? I forget...
unsigned int *map = qmap->mq_map; unsigned int nr_queues = qmap->nr_queues; - unsigned int cpu, first_sibling, q = 0; + unsigned int q;- for_each_possible_cpu(cpu)- map[cpu] = -1; + masks = irq_create_affinity_masks(nr_queues, &affd); + if (!masks) + return -ENOMEM;
should we fall back on something else here? Seems that this function does not fail just because out of memory.
Thanks, John
