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authorChristoph Hellwig <hch@lst.de>2016-09-14 17:18:52 +0300
committerJens Axboe <axboe@fb.com>2016-09-15 17:42:03 +0300
commit4e68a011428af3211facd932b4003b3fa3ef4faa (patch)
tree474b74a7761809a683a4a7d17576d95568e94a33 /block
parent474b313de79e034e269955de23231da769a521b7 (diff)
downloadlinux-4e68a011428af3211facd932b4003b3fa3ef4faa.tar.xz
blk-mq: don't redistribute hardware queues on a CPU hotplug event
Currently blk-mq will totally remap hardware context when a CPU hotplug even happened, which causes major havoc for drivers, as they are never told about this remapping. E.g. any carefully sorted out CPU affinity will just be completely messed up. The rebuild also doesn't really help for the common case of cpu hotplug, which is soft onlining / offlining of cpus - in this case we should just leave the queue and irq mapping as is. If it actually worked it would have helped in the case of physical cpu hotplug, although for that we'd need a way to actually notify the driver. Note that drivers may already be able to accommodate such a topology change on their own, e.g. using the reset_controller sysfs file in NVMe will cause the driver to get things right for this case. With the rebuild removed we will simplify retain the queue mapping for a soft offlined CPU that will work when it comes back online, and will map any newly onlined CPU to queue 0 until the driver initiates a rebuild of the queue map. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block')
-rw-r--r--block/blk-mq.c2
1 files changed, 0 insertions, 2 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 7ddc7969fba4..ffc9d4a3dbbd 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2157,8 +2157,6 @@ static void blk_mq_queue_reinit(struct request_queue *q,
blk_mq_sysfs_unregister(q);
- blk_mq_update_queue_map(q->mq_map, q->nr_hw_queues, online_mask);
-
/*
* redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
* we should change hctx numa_node according to new topology (this