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SubjectRe: 2.6.27.8: OOM killer: [swapper: page allocation failure]
On Fri, Dec 12, 2008 at 5:14 AM, Justin Piszcz <jpiszcz@lucidpixels.com> wrote:
> Kernel: 2.6.27.8
>
> I have a RAID-6 volume with 6 disks:
> mdadm --create -v /dev/md0 --level=6 -n 6 -e 0.90 /dev/sd[e-j]1
>
> While it is building...
>
> # cat /proc/mdstat
> Personalities : [raid1] [raid6] [raid5] [raid4]
> md0 : active raid6 sdj1[5] sdi1[4] sdh1[3] sdg1[2] sdf1[1] sde1[0]
> 1562834944 blocks level 6, 64k chunk, algorithm 2 [6/6] [UUUUUU]
> [===>.................] resync = 19.0% (74237440/390708736)
> finish=346.7min speed=15208K/sec
>
> unused devices: <none>
>
> During this time, I am copying files to it at ~60-100MiB/s using 2 rsyncs
> over NFS from 2 separate machines => this one [over the network] (on a pci-e
> x1 / built-in to the motherboard).
>
> top output:
> top - 07:10:06 up 12:32, 30 users, load average: 3.46, 4.49, 4.39
> Tasks: 316 total, 2 running, 313 sleeping, 1 stopped, 0 zombie
> Cpu(s): 12.1%us, 3.7%sy, 0.0%ni, 32.5%id, 49.2%wa, 1.1%hi, 1.2%si,
> 0.0%st
> Mem: 8100836k total, 8057480k used, 43356k free, 0k buffers
> Swap: 16787884k total, 144k used, 16787740k free, 6609412k cached
>
> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
> 5349 root 15 -5 0 0 0 R 10 0.0 11:59.94 md0_raid5
> 1 root 20 0 10312 748 620 S 0 0.0 0:02.14 init
>
> I see this over and over in the kernel log (maybe it will stop when the
> RAID6
> rebuild is completed)? So far, my rsyncs are continuing just fine and
> nothing except klogd/swapper processes have been killed.
>
> [44893.846532] swapper: page allocation failure. order:0, mode:0x20
[..]
>
> Raid optimizations used:
>
> # cat oraid.sh |grep -v ^#|grep .
> . /etc/profile
> echo "Optimizing RAID Arrays..."
> cd /sys/block
> DISKS=$(/bin/ls -1d sd[e-j])
> echo "Setting read-ahead to 32 MiB for /dev/md0"
> blockdev --setra 65536 /dev/md0
> echo "Setting stripe_cache_size to 16 MiB for /dev/md0"
> echo 16384 > /sys/block/md0/md/stripe_cache_size
>

If you set the stripe_cache_size high enough you can strangle the
system. Do you really need 384MiB of raid cache?


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