From: Jeff Moyer <jmoyer@redhat.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-kernel@vger.kernel.org
Subject: Re: blk_mq_update_queue_map makes an (invalid?) assumption about cpu ordering
Date: Tue, 15 Oct 2013 14:25:00 -0400 [thread overview]
Message-ID: <x491u3mpf2b.fsf@segfault.boston.devel.redhat.com> (raw)
In-Reply-To: <20131015181403.GY541@kernel.dk> (Jens Axboe's message of "Tue, 15 Oct 2013 12:14:03 -0600")
Jens Axboe <axboe@kernel.dk> writes:
>> 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?
>
> That's correct, it's assuming the first sibling is the lowest numbered
> one. Are there cases where that would not be correct? I was sort of
> assuming that was what "first" meant here.
Yeah, you're right. I hadn't read down the call chain:
static int get_first_sibling(unsigned int cpu)
ret = cpumask_first(topology_thread_cpumask(cpu));
Nothing to see here, move along...
-Jeff
prev parent reply other threads:[~2013-10-15 18:25 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-15 17:52 Jeff Moyer
2013-10-15 18:14 ` Jens Axboe
2013-10-15 18:25 ` Jeff Moyer [this message]
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