From: Peter Zijlstra <peterz@infradead.org>
To: Ming Lei <ming.lei@redhat.com>
Cc: Bart Van Assche <bvanassche@acm.org>,
mingo@redhat.com, will.deacon@arm.com, tj@kernel.org,
longman@redhat.com, johannes.berg@intel.com,
linux-kernel@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
Theodore Ts'o <tytso@mit.edu>
Subject: Re: [PATCH v7 21/23] block: Avoid that flushing triggers a lockdep complaint
Date: Wed, 27 Feb 2019 15:24:51 +0100 [thread overview]
Message-ID: <20190227142451.GQ32494@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20190227013555.GA16802@ming.t460p>
On Wed, Feb 27, 2019 at 09:35:56AM +0800, Ming Lei wrote:
> On Tue, Feb 26, 2019 at 07:08:02PM +0100, Peter Zijlstra wrote:
> > On Fri, Feb 15, 2019 at 10:26:59AM +0800, Ming Lei wrote:
> > > There might be lots of blk_flush_queue instance which is allocated
> > > for each hctx, then lots of class key slot may be wasted.
> >
> > What is 'lots' ? for someone who doesn't really know all that much about
> > the block layer.
>
> Each hw queue has one instance of blk_flush_queue, and one device may
> has lots of hw queues(may be > all possible cpus, such as nvme), and there
> may be lots of block devices in one system.
>
> Suppose one system has 10 NVMe hosts, 8 disks attached to each host, and
> 256 CPU cores in the system, there can be 10 * 8 * 256 = 20K instances of
> blk_flush_queue.
>
> Not mention there are other block devices(loop, nbd, scsi, ...) in the system.
>
> That is why I suggest to use one single lock class for addressing this
> nvme loop specific issue:
>
> https://marc.info/?l=linux-kernel&m=155019765724564&w=2
Right; that is rather a lot. But what causes the recursion, and thus how
is it specific to NVME ?
next prev parent reply other threads:[~2019-02-27 14:25 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-14 23:00 [PATCH v7 00/23] locking/lockdep: Add support for dynamic keys Bart Van Assche
2019-02-14 23:00 ` [PATCH v7 01/23] locking/lockdep: Fix two 32-bit compiler warnings Bart Van Assche
2019-02-28 7:02 ` [tip:locking/core] " tip-bot for Bart Van Assche
2019-02-14 23:00 ` [PATCH v7 02/23] locking/lockdep: Fix reported required memory size (1/2) Bart Van Assche
2019-02-28 7:03 ` [tip:locking/core] " tip-bot for Bart Van Assche
2019-02-14 23:00 ` [PATCH v7 03/23] locking/lockdep: Fix reported required memory size (2/2) Bart Van Assche
2019-02-28 7:03 ` [tip:locking/core] " tip-bot for Bart Van Assche
2019-02-14 23:00 ` [PATCH v7 04/23] locking/lockdep: Avoid that add_chain_cache() adds an invalid chain to the cache Bart Van Assche
2019-02-28 7:04 ` [tip:locking/core] " tip-bot for Bart Van Assche
2019-02-14 23:00 ` [PATCH v7 05/23] locking/lockdep: Reorder struct lock_class members Bart Van Assche
2019-02-28 7:05 ` [tip:locking/core] " tip-bot for Bart Van Assche
2019-02-14 23:00 ` [PATCH v7 06/23] locking/lockdep: Make zap_class() remove all matching lock order entries Bart Van Assche
2019-02-28 7:05 ` [tip:locking/core] " tip-bot for Bart Van Assche
2019-02-14 23:00 ` [PATCH v7 07/23] locking/lockdep: Initialize the locks_before and locks_after lists earlier Bart Van Assche
2019-02-28 7:06 ` [tip:locking/core] " tip-bot for Bart Van Assche
2019-02-14 23:00 ` [PATCH v7 08/23] locking/lockdep: Split lockdep_free_key_range() and lockdep_reset_lock() Bart Van Assche
2019-02-28 7:07 ` [tip:locking/core] " tip-bot for Bart Van Assche
2019-02-14 23:00 ` [PATCH v7 09/23] locking/lockdep: Make it easy to detect whether or not inside a selftest Bart Van Assche
2019-02-28 7:07 ` [tip:locking/core] " tip-bot for Bart Van Assche
2019-02-14 23:00 ` [PATCH v7 10/23] locking/lockdep: Update two outdated comments Bart Van Assche
2019-02-28 7:08 ` [tip:locking/core] " tip-bot for Bart Van Assche
2019-02-14 23:00 ` [PATCH v7 11/23] locking/lockdep: Free lock classes that are no longer in use Bart Van Assche
2019-02-28 7:09 ` [tip:locking/core] " tip-bot for Bart Van Assche
2019-02-14 23:00 ` [PATCH v7 12/23] locking/lockdep: Reuse list entries " Bart Van Assche
2019-02-28 7:09 ` [tip:locking/core] " tip-bot for Bart Van Assche
2019-02-14 23:00 ` [PATCH v7 13/23] locking/lockdep: Introduce lockdep_next_lockchain() and lock_chain_count() Bart Van Assche
2019-02-28 7:10 ` [tip:locking/core] " tip-bot for Bart Van Assche
2019-02-14 23:00 ` [PATCH v7 14/23] locking/lockdep: Fix a comment in add_chain_cache() Bart Van Assche
2019-02-28 7:11 ` [tip:locking/core] " tip-bot for Bart Van Assche
2019-02-14 23:00 ` [PATCH v7 15/23] locking/lockdep: Reuse lock chains that have been freed Bart Van Assche
2019-02-28 7:11 ` [tip:locking/core] " tip-bot for Bart Van Assche
2019-02-14 23:00 ` [PATCH v7 16/23] locking/lockdep: Check data structure consistency Bart Van Assche
2019-02-28 7:12 ` [tip:locking/core] " tip-bot for Bart Van Assche
2019-02-14 23:00 ` [PATCH v7 17/23] locking/lockdep: Verify whether lock objects are small enough to be used as class keys Bart Van Assche
2019-02-28 7:13 ` [tip:locking/core] " tip-bot for Bart Van Assche
2019-02-14 23:00 ` [PATCH v7 18/23] locking/lockdep: Add support for dynamic keys Bart Van Assche
2019-02-26 17:17 ` Peter Zijlstra
2019-02-28 7:13 ` [tip:locking/core] " tip-bot for Bart Van Assche
2019-02-14 23:00 ` [PATCH v7 19/23] kernel/workqueue: Use dynamic lockdep keys for workqueues Bart Van Assche
2019-02-28 7:14 ` [tip:locking/core] " tip-bot for Bart Van Assche
2019-02-14 23:00 ` [PATCH v7 20/23] locking/spinlock: Introduce spin_lock_init_key() Bart Van Assche
2019-02-14 23:00 ` [PATCH v7 21/23] block: Avoid that flushing triggers a lockdep complaint Bart Van Assche
2019-02-15 2:26 ` Ming Lei
2019-02-15 16:08 ` Bart Van Assche
2019-02-17 13:23 ` Ming Lei
2019-02-26 18:08 ` Peter Zijlstra
2019-02-27 1:35 ` Ming Lei
2019-02-27 14:24 ` Peter Zijlstra [this message]
2019-02-27 15:53 ` Ming Lei
2019-02-26 17:24 ` Peter Zijlstra
2019-02-26 17:48 ` Bart Van Assche
2019-02-14 23:00 ` [PATCH v7 22/23] lockdep tests: Fix run_tests.sh Bart Van Assche
2019-02-28 7:15 ` [tip:locking/core] lockdep/lib/tests: " tip-bot for Bart Van Assche
2019-02-14 23:00 ` [PATCH v7 23/23] lockdep tests: Test dynamic key registration Bart Van Assche
2019-02-28 7:15 ` [tip:locking/core] lockdep/lib/tests: " tip-bot for Bart Van Assche
2019-02-21 22:02 ` [PATCH v7 00/23] locking/lockdep: Add support for dynamic keys Bart Van Assche
2019-02-22 16:26 ` Peter Zijlstra
2019-02-22 17:20 ` Bart Van Assche
2019-02-22 22:13 ` Peter Zijlstra
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190227142451.GQ32494@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=axboe@kernel.dk \
--cc=bvanassche@acm.org \
--cc=johannes.berg@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=longman@redhat.com \
--cc=ming.lei@redhat.com \
--cc=mingo@redhat.com \
--cc=tj@kernel.org \
--cc=tytso@mit.edu \
--cc=will.deacon@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).