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From: Christoph Hellwig <hch@lst.de>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	"Darrick J. Wong" <djwong@kernel.org>,
	Dennis Zhou <dennis@kernel.org>, Tejun Heo <tj@kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	linux-xfs <linux-xfs@vger.kernel.org>,
	Dave Chinner <david@fromorbit.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Eric Sandeen <sandeen@sandeen.net>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [GIT PULL] xfs: new code for 5.15
Date: Fri, 3 Sep 2021 06:29:37 +0200	[thread overview]
Message-ID: <20210903042937.GA21466@lst.de> (raw)
In-Reply-To: <87wnnybxkb.ffs@tglx>

On Thu, Sep 02, 2021 at 09:13:24PM +0200, Thomas Gleixner wrote:
> > I'm only throwing this out as a reaction to this - I'm not sure
> > another interface would be good or worthwhile, but that "enum
> > cpuhp_state" is ugly enough that I thought I'd rope in Thomas for CPU
> > hotplug, and the percpu memory allocation people for comments.
> 
> It's not only about memory. 
> 
> > IOW, just _maybe_ we would want to have some kind of callback model
> > for "percpu_alloc()" and it being explicitly about allocations
> > becoming available or going away, rather than about CPU state.
> 
> The per cpu storage in XFS does not go away. It contains a llist head
> and the queued work items need to be moved from the dead CPU to an alive
> CPU and exposed to a work queue for processing. Similar to what we do
> with timers, hrtimers and other stuff.
> 
> If there are callbacks which are doing pretty much the same thing, then
> I'm all for a generic infrastructure for these.

In the block layer we've added a new per-cpu bio list, for which
the dead callback literally does nothing but free some memory.
For that case a simple callback would be neat, but I'm not sure how
common that is.

  reply	other threads:[~2021-09-03  4:29 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-31 21:18 Darrick J. Wong
2021-09-02 15:47 ` Linus Torvalds
2021-09-02 17:43   ` Darrick J. Wong
2021-09-02 22:35     ` Dave Chinner
2021-09-03  6:26       ` Thomas Gleixner
2021-09-05  0:21         ` Dave Chinner
2021-09-05 23:28           ` Thomas Gleixner
2021-09-06  2:11             ` Randy Dunlap
2021-09-06  9:42               ` Thomas Gleixner
2021-09-02 19:13   ` Thomas Gleixner
2021-09-03  4:29     ` Christoph Hellwig [this message]
2021-09-03 18:40   ` Dennis Zhou
2021-09-02 17:37 ` pr-tracker-bot

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