From b4e75cbf1364c4bbce3599c3279892a55b6ede07 Mon Sep 17 00:00:00 2001 From: Sam Bradshaw Date: Fri, 9 May 2014 13:27:07 -0700 Subject: [PATCH] NVMe: Adhere to request queue block accounting enable/disable Recently, a new sysfs control "iostats" was added to selectively enable or disable io statistics collection for request queues. This patch hooks that control. IO statistics collection is rather expensive on large, multi-node machines with drives pushing millions of iops. Having the ability to disable collection if not needed can improve throughput significantly. As a data point, on a quad E5-4640, I see more than 50% throughput improvement when io statistics accounting is disabled during heavily multi-threaded small block random read benchmarks where device performance is in the million iops+ range. Signed-off-by: Sam Bradshaw Signed-off-by: Matthew Wilcox --- drivers/block/nvme-core.c | 33 +++++++++++++++++++-------------- 1 file changed, 19 insertions(+), 14 deletions(-) diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c index 29a3e85873b5..bb6ce311ad44 100644 --- a/drivers/block/nvme-core.c +++ b/drivers/block/nvme-core.c @@ -406,25 +406,30 @@ void nvme_free_iod(struct nvme_dev *dev, struct nvme_iod *iod) static void nvme_start_io_acct(struct bio *bio) { struct gendisk *disk = bio->bi_bdev->bd_disk; - const int rw = bio_data_dir(bio); - int cpu = part_stat_lock(); - part_round_stats(cpu, &disk->part0); - part_stat_inc(cpu, &disk->part0, ios[rw]); - part_stat_add(cpu, &disk->part0, sectors[rw], bio_sectors(bio)); - part_inc_in_flight(&disk->part0, rw); - part_stat_unlock(); + if (blk_queue_io_stat(disk->queue)) { + const int rw = bio_data_dir(bio); + int cpu = part_stat_lock(); + part_round_stats(cpu, &disk->part0); + part_stat_inc(cpu, &disk->part0, ios[rw]); + part_stat_add(cpu, &disk->part0, sectors[rw], + bio_sectors(bio)); + part_inc_in_flight(&disk->part0, rw); + part_stat_unlock(); + } } static void nvme_end_io_acct(struct bio *bio, unsigned long start_time) { struct gendisk *disk = bio->bi_bdev->bd_disk; - const int rw = bio_data_dir(bio); - unsigned long duration = jiffies - start_time; - int cpu = part_stat_lock(); - part_stat_add(cpu, &disk->part0, ticks[rw], duration); - part_round_stats(cpu, &disk->part0); - part_dec_in_flight(&disk->part0, rw); - part_stat_unlock(); + if (blk_queue_io_stat(disk->queue)) { + const int rw = bio_data_dir(bio); + unsigned long duration = jiffies - start_time; + int cpu = part_stat_lock(); + part_stat_add(cpu, &disk->part0, ticks[rw], duration); + part_round_stats(cpu, &disk->part0); + part_dec_in_flight(&disk->part0, rw); + part_stat_unlock(); + } } static void bio_completion(struct nvme_queue *nvmeq, void *ctx, -- 2.30.2