RE: /proc/stat vs. failed order-4 allocation

From: Elliott, Robert (Server Storage)
Date: Wed May 21 2014 - 23:08:31 EST




> -----Original Message-----
> From: linux-kernel-owner@xxxxxxxxxxxxxxx [mailto:linux-kernel-
> owner@xxxxxxxxxxxxxxx] On Behalf Of Christoph Hellwig
> Sent: Wednesday, May 21, 2014 9:32 AM
> To: Heiko Carstens
> Cc: Andrew Morton; KAMEZAWA Hiroyuki; Andrea Righi; Eric Dumazet; linux-
> kernel@xxxxxxxxxxxxxxx; linux-fsdevel@xxxxxxxxxxxxxxx; Hendrik Brueckner;
> Thorsten Diehl
> Subject: Re: /proc/stat vs. failed order-4 allocation
>
> On Wed, May 21, 2014 at 02:25:21PM +0200, Heiko Carstens wrote:
> > Hi all,
> >
> > I'm just wondering why /proc/stat is a single_open() seq_file and not a
> > regular seq_file with an iterator (say 48 online cpus for each iteration
> > or something similar).
>
> Probably because no one sent a patch for it. I'm pretty sure it used the
> even more horrible old proc ops before and was converted in batch with
> various other files.

https://lkml.org/lkml/2012/1/20/153 worried about performance and led to
the current code; the reply in https://lkml.org/lkml/2012/1/23/41
discussed using seq_file, but that idea was rejected at the time.

Be careful about losing consistency of the information for the CPUs.

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