From: Jeff Moyer <jmoyer@redhat.com>
To: jaxboe@fusionio.com
Cc: linux-kernel@vger.kernel.org
Subject: blk_mq_update_queue_map makes an (invalid?) assumption about cpu ordering
Date: Tue, 15 Oct 2013 13:52:50 -0400 [thread overview]
Message-ID: <x49fvs2pgjx.fsf@segfault.boston.devel.redhat.com> (raw)
Hi, Jens,
blk_mq_update_queue_map does this:
for_each_possible_cpu(i) {
if (!cpu_online(i)) {
map[i] = 0;
continue;
}
...
first_sibling = get_first_sibling(i);
if (first_sibling == i) {
map[i] = cpu_to_queue_index(nr_uniq_cpus, nr_queues,
queue);
queue++;
} else
map[i] = map[first_sibling];
This assumes that the first_sibling is listed before any other siblings,
which I don't believe is true. I don't think you get any guaranteed
ordering in that cpu_possible_mask.
... or did I miss something?
Cheers,
Jeff
next reply other threads:[~2013-10-15 17:52 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-15 17:52 Jeff Moyer [this message]
2013-10-15 18:14 ` Jens Axboe
2013-10-15 18:25 ` Jeff Moyer
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