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From: Greg KH <gregkh@linuxfoundation.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] char_dev: replace cdev_map with an xarray
Date: Mon, 11 Jan 2021 19:11:25 +0100	[thread overview]
Message-ID: <X/yUzVu04TyVuU/f@kroah.com> (raw)
In-Reply-To: <20210111173500.GG35215@casper.infradead.org>

On Mon, Jan 11, 2021 at 05:35:00PM +0000, Matthew Wilcox wrote:
> On Mon, Jan 11, 2021 at 06:05:13PM +0100, Christoph Hellwig wrote:
> > None of the complicated overlapping regions bits of the kobj_map are
> > required for the character device lookup, so just a trivial xarray
> > instead.
> 
> Thanks for doing this.  We could make it more efficient for chardevs
> that occupy 64 or more consecutive/aligned devices -- is it worth doing?

efficient in what way?  Space or faster lookup?

THis shouldn't be on a "fast" lookup path, so I doubt that's worth
optimizing for.  Space, maybe, for systems with thousands of scsi
devices, but usually they just stick to the block device, not a char
device from what I remember.

thanks,

greg k-h

  reply	other threads:[~2021-01-11 18:12 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-11 17:05 [PATCH] char_dev: replace cdev_map with an xarray Christoph Hellwig
2021-01-11 17:35 ` Matthew Wilcox
2021-01-11 18:11   ` Greg KH [this message]
2021-01-11 18:20     ` Matthew Wilcox
2021-01-11 18:33       ` Greg KH
2021-01-11 18:51         ` Matthew Wilcox
2021-01-11 18:10 ` Greg KH
2021-01-11 20:58 ` Matthew Wilcox
2021-01-12  9:35   ` Greg KH
2021-01-12 10:00     ` David Laight
2021-01-12 10:25       ` 'Greg KH'

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