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From: Nadia Derbey <Nadia.Derbey@bull.net>
To: Michael Kerrisk <mtk.manpages@googlemail.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-mm@vger.kernel.org
Subject: Re: [PATCH 1/8] Scaling msgmni to the amount of lowmem
Date: Tue, 20 May 2008 16:45:55 +0200	[thread overview]
Message-ID: <4832E423.5040708@bull.net> (raw)
In-Reply-To: <cfd18e0f0805200728j1f38d90s1f6355b71e2d76@mail.gmail.com>

Michael Kerrisk wrote:
> Hello Nadia,
> 
> Regarding your:
> 
> [PATCH 1/8] Scaling msgmni to the amount of lowmem
> http://article.gmane.org/gmane.linux.kernel/637849/
> which I see has made its way in 2.6.26-rc
> 
> Your patch has the following change:
> 
> -#define MSGPOOL (MSGMNI*MSGMNB/1024)  /* size in kilobytes of message pool */
> +#define MSGPOOL (MSGMNI * MSGMNB) /* size in bytes of message pool */
> 
> Since this constitutes a kernel-userland interface change, so please
> do CC me, so that I can change the man pages if needed.

Oops, sorry for not doing it: I misunderstood the "unused"

> 
> The man page (http://www.kernel.org/doc/man-pages/online/pages/man2/msgctl.2.html)
> does indeed say that msgpool is "unused".  But that meant "unused by
> the kernel" (sorry -- I probably should have worded that text better).
>  And, as you spotted, the page also wrongly said the value is in
> bytes.
> 
> However, making this change affects the ABI.  A userspace application
> that was previously using msgctl(IPC_INFO) to retrieve the msgpool
> field will be affected by the factor-of-1024 change.  I strongly
> suspect that there no such applications, or certainly none that care
> (since this value is unused by the kernel).  But was there a reason
> for making this change, aside from the fact that the code and the man
> page didn't agree?
> 

No, that was the only reason.
Should I repost a patch to set it back as it used to be?

Regards
Nadia

  reply	other threads:[~2008-05-20 14:45 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-05-20 14:28 Michael Kerrisk
2008-05-20 14:45 ` Nadia Derbey [this message]
2008-05-20 14:56   ` Michael Kerrisk
2008-05-21 10:47   ` Michael Kerrisk
  -- strict thread matches above, loose matches on Subject: below --
2008-02-11 14:16 [PATCH 0/8] Change default MSGMNI tunable to scale with lowmem (v3) Nadia.Derbey
2008-02-11 14:16 ` [PATCH 1/8] Scaling msgmni to the amount of lowmem Nadia.Derbey
2008-02-16  5:59   ` Andrew Morton
2008-02-18  9:19     ` Nadia Derbey
2008-02-18 13:08       ` Nadia Derbey
2008-04-29 20:28   ` Tony Luck
2008-05-05  8:45     ` Nadia Derbey
2008-05-06 16:42       ` Luck, Tony
2008-05-06 18:05         ` Serge E. Hallyn
2008-05-07  5:37           ` Nadia Derbey
2008-05-07 13:17             ` Serge E. Hallyn
2008-05-07 18:12               ` Matt Helsley
2008-05-07  5:13         ` Nadia Derbey

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