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From: Peter Zijlstra <peterz@infradead.org>
To: Pavel Machek <pavel@ucw.cz>
Cc: Andrew Morton <akpm@osdl.org>,
	kernel list <linux-kernel@vger.kernel.org>,
	andrea@suse.de, npiggin@suse.de
Subject: Re: min_free_kbytes documentation, /proc/sys/vm docs
Date: Mon, 13 Aug 2007 15:53:00 +0200	[thread overview]
Message-ID: <1187013180.20108.59.camel@twins> (raw)
In-Reply-To: <20070813134626.GA7305@atrey.karlin.mff.cuni.cz>

On Mon, 2007-08-13 at 15:46 +0200, Pavel Machek wrote:
> Hi!
> 
> min_free_kbytes documentation says:
> 
> min_free_kbytes:
> 
> This is used to force the Linux VM to keep a minimum number 
> of kilobytes free.  The VM uses this number to compute a pages_min
> value for each lowmem zone in the system.  Each lowmem zone gets 
> a number of reserved free pages based proportionally on its size.
> 
> ....which is not too helpful :-(. In particular, should kernel survive
> setting this to 0 and still work reliably? IOW is this
> performance-only tweak, or does it correctness implications?

correctness

sort-of, since PF_MEMALLOC usage is currently un-bounded.

> I guess it should also say something like "do not set this to more
> than half of your physical RAM (or half of lowmem?) or you get an
> instant OOM".

yeah, lowmem, not sure on the oom part, it should work with quite high
limits, although I've never tried it with ridiculous numbers.


  reply	other threads:[~2007-08-13 15:41 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-08-13 13:46 min_free_kbytes documentation, /proc/sys/vm docs Pavel Machek
2007-08-13 13:53 ` Peter Zijlstra [this message]
2007-08-13 14:12   ` Pavel Machek

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