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From: "H. Peter Anvin" <>
To: Hugh Dickins <>
Cc: Tomasz Chmielewski <>,
	LKML <>,
	Mika Lawando <>
Subject: Re: What is the limit size of tmpfs /dev/shm ?
Date: Wed, 06 Feb 2008 11:53:19 -0800	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

Hugh Dickins wrote:
> In theory, yes, and should be true in practice before it hits swap.
> But I think you'll find our swap handling is too primitive for tmpfs
> to perform well once we hit swap.  Most filesystems pay considerable
> attention to good performance within their constraints of correctness.
> Whereas with tmpfs we've just never worried about the performance once
> swapping.  It's used so you don't lose your data, but if you're really
> expecting to be going to disk very much, better start with a filesystem
> really designed for that.

That sounds like a problem in our overall swap handling, not 
specifically in tmpfs.  Now, I can't say anything concrete about heavy 
swap conditions, but in light swap conditions I have measured a 20x 
performance improvement(!) over ext3 on real workloads.


  reply	other threads:[~2008-02-06 19:53 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-06 14:54 Tomasz Chmielewski
2008-02-06 15:06 ` rzryyvzy
2008-02-06 15:29 ` Hugh Dickins
2008-02-06 19:27   ` H. Peter Anvin
2008-02-06 19:48     ` Hugh Dickins
2008-02-06 19:53       ` H. Peter Anvin [this message]
2008-02-06 21:58         ` Hugh Dickins
2008-02-06 22:01           ` H. Peter Anvin
2008-02-06 22:40             ` Hugh Dickins
  -- strict thread matches above, loose matches on Subject: below --
2008-02-06 13:54 Mika Lawando

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