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From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Kumar Gala <galak@kernel.crashing.org>
Cc: Linux Kernel list <linux-kernel@vger.kernel.org>
Subject: Re: tuning/tweaking VM settings for low memory (preventing OOM)
Date: Sat, 13 Jan 2007 15:54:15 +1100	[thread overview]
Message-ID: <45A865F7.3010900@yahoo.com.au> (raw)
In-Reply-To: <D7BBB18A-F5D4-4FE0-903F-3683333D957C@kernel.crashing.org>

Kumar Gala wrote:
> I'm working on an embedded PPC setup with 64M of memory and no swap.   
> I'm trying to figure out how best to tune the VM for an OOM situation  
> I'm running into.
> 
> I'm running a 2.6.16.35 kernel and have a bittorrent app that appears  
> to be initializing a large file for it to download into.  What I see  
> before running the app:
> 
> /bigfoot/usb_disk # cat /proc/meminfo
> MemTotal:        62520 kB
> MemFree:         49192 kB
> Buffers:          8240 kB
> Cached:            740 kB
> SwapCached:          0 kB
> Active:           8196 kB
> Inactive:         1236 kB
> HighTotal:           0 kB
> HighFree:            0 kB
> LowTotal:        62520 kB
> LowFree:         49192 kB
> SwapTotal:           0 kB
> SwapFree:            0 kB
> Dirty:               0 kB
> Writeback:           0 kB
> Mapped:            916 kB
> Slab:             2224 kB
> CommitLimit:     31260 kB
> Committed_AS:     1704 kB
> PageTables:         88 kB
> VmallocTotal:   933872 kB
> VmallocUsed:      9416 kB
> VmallocChunk:   923628 kB
> 
> after the OOM:
> 
> /bigfoot/usb_disk # cat /proc/meminfo
> MemTotal:        62520 kB
> MemFree:          1608 kB
> Buffers:          8212 kB
> Cached:          42780 kB
> SwapCached:          0 kB
> Active:           6228 kB
> Inactive:        45176 kB
> HighTotal:           0 kB
> HighFree:            0 kB
> LowTotal:        62520 kB
> LowFree:          1608 kB
> SwapTotal:           0 kB
> SwapFree:            0 kB
> Dirty:           35208 kB
> Writeback:        5616 kB
> Mapped:            892 kB
> Slab:             7788 kB
> CommitLimit:     31260 kB
> Committed_AS:     1704 kB
> PageTables:         88 kB
> VmallocTotal:   933872 kB
> VmallocUsed:      9416 kB
> VmallocChunk:   923628 kB
> 
> Which makes me think that we aren't writing back fast enough.  If I  
> mount the drive "sync" the issue clearly goes away.
> 
> It appears from an strace we are doing ftruncate64(5, 178257920) when  
> we OOM.
> 
> Any ideas on VM parameters to tweak so we throttle this from occurring?

You don't give us the actual OOM message. In newer kernels, there has been
quite a bit of work done to improve the OOM situation -- search changelogs
in mm/oom_kill.c mm/vmscan.c mm/page_alloc.c.

-- 
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com 

  reply	other threads:[~2007-01-13  4:54 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-01-12 21:58 Kumar Gala
2007-01-13  4:54 ` Nick Piggin [this message]
2007-01-15 17:13   ` Kumar Gala
2007-01-13  7:22 ` Willy Tarreau
2007-01-13 13:16   ` Toon van der Pas
2007-01-13 14:30     ` Willy Tarreau
2007-01-13 23:58       ` Toon van der Pas

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